grapesjs/docs/modules/Components.md

title
Component Manager

Component Manager

The Component is the base element for template composition. It is atomic, so elements like images, text boxes, maps, etc. fit the definition of a Component. The concept of the component was made to allow the developer to bind different behaviors to different elements. Like for example, opening the Asset Manager on double click of the image.

::: warning This guide is referring to GrapesJS v0.14.67 or higher :::

toc

How Components work?

Let's see in detail how components work by looking at all steps from adding an HTML string to the editor.

This is how we can add new components to the canvas:

// Append components directly to the canvas
editor.addComponents(`<div>
  <img src="https://path/image" />
  <span title="foo">Hello world!!!</span>
</div>`);

// or into some, already defined, component.
// For instance, appending to a selected component would be:
editor.getSelected().append(`<div>...`);

// Actually, editor.addComponents is an alias of...
editor.getWrapper().append(`<div>...`);

::: tip If you need to append a component in a specific position, you can use at option. To add a component on top of all others (in the same collection) you would use

component.append('<div>...', { at: 0 })

or in the middle

const { length } = component.components();
component.append('<div>...', { at: parseInt(length / 2, 10) })

:::

Component Definition

In the first step the HTML string is parsed and trasformed to what is called Component Definition, so the result of the input would be:

{
  tagName: 'div',
  components: [
    {
      type: 'image',
      attributes: { src: 'https://path/image' },
    }, {
      tagName: 'span',
      type: 'text',
      attributes: { title: 'foo' },
      components: [{
        type: 'textnode',
        content: 'Hello wdsforld!!!'
      }]
    }
  ]
}

The real Component Definition would be a little bit bigger so we reduced the JSON for the sake of simplicity.

You can notice the result is similar to what is generally called a Virtual DOM, a lightweight rappresentation of the DOM element. This actually helps the editor to keep track of the state of our elements and make performance-friendly changes/updates. The meaning of properties like tagName, attributes and components are quite obvious, but what about type?! This particular property specifies the actual Component of our Component Definition (you check the list of default components below) and if it's omitted, the default one will be used type: 'default'. At this point, a good question would be, how the editor assignes those types by starting from a simple HTML string? This step is identified as Component Recognition and it's explained in detail in the next paragraph.

Component Recognition and Component Type Stack

As we said before, when you pass an HTML string as a component to the editor, that string is parsed and compiled to the Component Definition with a new type property. To understand what type should be assigned, for each parsed HTML Element, the editor iterates over all the defined components, called Component Type Stack, and checks via isComponent method (we will see it later) if that component type is appropriate for that element. The Component Type Stack is just a simple array of components but the important part is the order of those components. Any new added Custom Component (we'll see later how to create them) goes on top of the Component Type Stack and each element returned from the parser iterates the stack from top to bottom (the last element of the stack is the default one), the iteration stops once one of the component returns a truthy value from the isComponent method.

SVG - ComponentTypeStack

::: tip If you're importing big chunks of HTML code you might want to improve the performances by skipping the parsing and the component recognition steps by passing directly Component Definiton objects or using the JSX syntax. Read more about it here...TODO :::

Component Creation

Once the Component Definition is ready and the type is assigned, the Component instance can be created (known also as the Model). Let's step back to our previous example with the HTML string, the result of the append method is an array of added components.

const component = editor.addComponents(`<div>
  <img src="https://path/image" />
  <span title="foo">Hello world!!!</span>
</div>`)[0];

The Component instance contains properties and methods which allows you to obtain its data and change them. You can read properties with the get method, like, for example, the type

const componentType = component.get('type'); // eg. 'image'

and to update properties you'd use set, which might change the way a component behavies in the canvas.

// Make the component not draggable
component.set('draggable', false);

You can also use methods like getAttributes, setAttributes, components, etc.

const innerComponents = component.components();
// Update component content
component.components(`<div>Component 1</div><div>Component 2</div>`);

Each component can define its own properties and methods but all of them will always extend, at least, the default one (then you will see how to create new custom components and how to extend the already defined) so it's good to check the Component API to see all available properties and methods.

The main purpose of the Component is to keep track of its data and to return them when necessary. One common thing you might need to ask from the component is to show its current HTML

const componentHTML = component.toHTML();

This will return a string containing the HTML of the component and all of its children. The component implements also toJSON methods so you can get its JSON structure in this way

JSON.stringify(component)

::: tip For storing/loading all the components you should rely on the Storage Manager :::

The Component instance is responable for the final data (eg. HTML, JSON) of your templates, so if you need, for example, to update/add some attribute in the HTML you need to update its component (eg. component.addAttributes({ title: 'Title added' })), so the Component/Model is your Source of Truth.

Component Rendering

Another important thing of components is how they are rendered in the canvas, this aspect is handled by the View of the component. It has nothing to do with the final data, you can return a big <div>...</div> string as HTML of your component but render it as a simple image in the canvas (think about placeholders for complex/dynamic data).

So, by default, the view of components is automatically synced with the data of its models (you can't have a View without a Model). If you update the attribute of the component or append a new one as a child, the view will render it in the canvas. Unfotunatelly, sometimes, you might need some additional logic to handle better the component result. Think about allowing a user build its <table> element, for this specific case you might want to add custom buttons in the canvas, so it'd be easier adding/removing columns/rows. To handle those cases you can rely on the View, where you can add additional DOM component, attach events, etc. All of this will be completely unrelated with the final HTML of the <table> (the result the user would expect) as it handled by the Model. Once the component is rendered (when you actually see it in the canvas) you can always access its View and the DOM element.

const component = editor.getSelected();
// Get the View
const view = component.getView();
// Get the DOM element
const el =  component.getEl();

So generally, the View is something you wouldn't need to change as the default one handles already the sync with the Model but in case you'd need more control over elements (eg. custom UI in canvas) you'll probably need to create a custom component and extend the default View with your logic. We'll see later how to create custom components.

So far we have seen the core concept behind Components and how they work. The Model/Component is the source of truth for the final code of templates (eg. the HTML export relies on it) and the View/ComponentView is what is used by the editor to preview our components to users in the canvas.

TODO A more advanced use case of custom components is an implementation of a custom renderer inside of them

Built-in Components

Here below you can see the list of built-in components, ordered by their position in the Component Type Stack

• cell - Component for handle <td> and <th> elements
• row - Component for handle <tr> elements
• table - Component for handle <table> elements
• thead - Component for handle <thead> elements
• tbody - Component for handle <tbody> elements
• tfoot - Component for handle <tfoot> elements
• map - Component for handle <a> elements
• link - Component for handle <a> elements
• label - Component for handle properly <label> elements
• video - Component for videos
• image - Component for images
• script - Component for handle <script> elements
• svg - Component for handle SVG elements
• comment - Component for comments (might be useful for email editors)
• textnode - Similar to the textnode in DOM definition, so a text element without a tag element.
• text - A simple text component that can be edited inline
• wrapper - The canvas need to contain a root component, a wrapper, this component was made to identify it
• default - Default base component

Define new Component

Now that we know how components work, we can start exploring the process of creating new Custom Components.

Let's say we want to make the editor understand and handle better <input> elements

First of all, place your components inside a plugin

--- OLD

Component recognition

But now, how does the editor recognize which Component to bind to the img element and what to do with the span one? Each Component inherits, from the base one, a particular static method

/**
 * @param {HTMLElement} el
 * @return {Object}
 */
isComponent: function(el) {
  ...
}

This method gives us the possibility to recognize and bind component types to each HTMLElement (div, img, iframe, etc.). Each HTML string/element introduced inside the canvas will be processed by isComponent of all available types and if it matches, the object represented the type should be returned. The method isComponent is skipped if you add the component object ({ type: 'my-custom-type', tagName: 'div', attribute: {...}, ...}) or declare the type explicitly on the element (<div data-gjs-type="my-custom-type">...</div>)

For example, with the image component this method looks like:

// Image component
isComponent: function(el) {
  if(el.tagName == 'IMG')
    return {type: 'image'};
}

Let's try with something that might look a little bit tricky. What about a Google Map?!? Google Maps are generally embedded as iframes, but the template can be composed by a lot of different iframes. How can I tell the editor that a particular iframe is actually a Google's Map? Well, you'll have to figure out the right pattern, you have the HTMLElement so you can make all the checks you want. In this particular case this pattern is used:

// Map component
isComponent: function(el) {
	if(el.tagName == 'IFRAME' && /maps\.google\.com/.test(el.src)) {
		return {type: 'map', src: el.src};
	}
},

In addition to tagName check, we also used the src property, but you can actually override it with your own logic by extending the built-in component.

Define new Component

Let's see an example with another HTML element that is not handled by default Component types. What about input elements?

With the default GrapesJS configuration inputs are treated like any other element; you can move it around, style it, etc. However, we'd like to handle this type of element more specifically. In this case, we have to create a new Component type.

Let's define few specs for our new Input type:

• Can be dropped only inside form elements
• Can't drop other elements inside it
• Can change the type of the input (text, password, email, etc.)
• Can make it required for the form

To define a new Component type you need to choose from which built-in Component inherit its properties, in our case we just gonna choose the default one. Let's see a complete example of the new type definition

// Get DomComponents module
var comps = editor.DomComponents;

// Get the model and the view from the default Component type
var defaultType = comps.getType('default');
var defaultModel = defaultType.model;
var defaultView = defaultType.view;

var inputTypes = [
  {value: 'text', name: 'Text'},
  {value: 'email', name: 'Email'},
  {value: 'password', name: 'Password'},
  {value: 'number', name: 'Number'},
];

// The `input` will be the Component type ID
comps.addType('input', {
  // Define the Model
  model: defaultModel.extend({
    // Extend default properties
    defaults: Object.assign({}, defaultModel.prototype.defaults, {
      // Can be dropped only inside `form` elements
      draggable: 'form, form *',
      // Can't drop other elements inside it
      droppable: false,
      // Traits (Settings)
      traits: ['name', 'placeholder', {
          // Change the type of the input (text, password, email, etc.)
          type: 'select',
          label: 'Type',
          name: 'type',
          options: inputTypes,
        },{
          // Can make it required for the form
          type: 'checkbox',
          label: 'Required',
          name: 'required',
      }],
    }),
  },
  // The second argument of .extend are static methods and we'll put inside our
  // isComponent() method. As you're putting a new Component type on top of the stack,
  // not declaring isComponent() might probably break stuff, especially if you extend
  // the default one.
  {
    isComponent: function(el) {
      if(el.tagName == 'INPUT'){
        return {type: 'input'};
      }
    },
  }),

  // Define the View
  view: defaultType.view,
});

The code above is pretty much self-explanatory and as you see a lot of work is basically done on top of the Model properties. The View is just extending the default one, so to cover also this part let's add some random behavior.

comps.addType('input', {
  model: {...},
  view: defaultType.view.extend({
    // Bind events
    events: {
      // If you want to bind the event to children elements
      // 'click .someChildrenClass': 'methodName',
      click: 'handleClick',
      dblclick: function(){
        alert('Hi!');
      }
    },

    // It doesn't make too much sense this method inside the component
    // but it's ok as an example
    randomHex: function() {
      return '#' + Math.floor(Math.random()*16777216).toString(16);
    },

    handleClick: function(e) {
      this.model.set('style', {color: this.randomHex()}); // <- Affects the final HTML code
      this.el.style.backgroundColor = this.randomHex(); // <- Doesn't affect the final HTML code
      // Tip: updating the model will reflect the changes to the view, so, in this case,
      // if you put the model change after the DOM one this will override the backgroundColor
      // change made before
    },

    // The render() should return 'this'
    render: function () {
      // Extend the original render method
      defaultType.view.prototype.render.apply(this, arguments);
      this.el.placeholder = 'Text here'; // <- Doesn't affect the final HTML code
      return this;
    },
  }),
});

From the example above you can notice few interesting things: how to bind events, how to update directly the DOM and how to update the model. The difference between updating the DOM and the model is that the HTML code (the one you get with editor.getHtml()) is generated from the Model so updating directly the DOM will not affect it, it's just the change for the canvas.

Update Component type

Here an example of how easily you can update/override the component

var originalMap = comps.getType('map');

comps.addType('map', {
  model: originalMap.model.extend({
    // Override how the component is rendered to HTML
    toHTML: function() {
      return '<div>My Custom Map</div>';
    },
  }, {
    isComponent: function(el) {
      // ... new logic for isComponent
		},
  }),
  view: originalMap.view
});

Improvement over addType

Now, with the 0.14.50 release, defining new components or extending them is a bit easier (without breaking the old process)

• If you don't specify the type to extend, the default one will be used. In that case, you just use objects for model and view
• The defaults property, in the model, will be merged automatically with defaults of the parent component
• If you use an object in model you can specify isComponent outside or omit it. In this case, the isComponent is not mandatory but without it means the parser won't be able to identify the component if not explicitly declared (eg. <div data-gjs-type="new-component">...</div>)

Before

const defaultType = comps.getType('default');

comps.addType('new-component', {
  model: defaultType.model.extend({
    defaults: {
      ...defaultType.model.prototype.defaults,
      someprop: 'somevalue',
    },
    ...
  }, {
    // Even if it returns false, declaring isComponent is mandatory
    isComponent(el) {
      return false;
    },
  }),
  view: defaultType.view.extend({ ... });
});

After

comps.addType('new-component', {
  // We can even omit isComponent here, as `false` return will be the default behavior
  isComponent: el => false,
  model: {
    defaults: {
      someprop: 'somevalue',
    },
    ...
  },
  view: { ... };
});

• If you need to extend some component, you can use extend and extendView property.
• You can now omit view property if you don't need to change it

Before

const originalMap = comps.getType('map');

comps.addType('map', {
  model: originalMap.model.extend({
    ...
  }, {
    isComponent(el) {
      // ... usually, you'd reuse the same logic
    },
  }),
  // Even if I do nothing in view, I have to specify it
  view: originalMap.view
});

After

The map type is already defined, so it will be used as a base for the model and view. We can skip isComponent if the recognition logic is the same of the extended component.

comps.addType('map', {
  model: { ... },
});

Extend the model and view with some other, already defined, components.

comps.addType('map', {
  extend: 'other-defined-component',
  model: { ... }, // Will extend 'other-defined-component'
  view: { ... }, // Will extend 'other-defined-component'
  // `isComponent` will be taken from `map`
});

comps.addType('map', {
  extend: 'other-defined-component',
  model: { ... }, // Will extend 'other-defined-component'
  extendView: 'other-defined-component-2',
  view: { ... }, // Will extend 'other-defined-component-2'
  // `isComponent` will be taken from `map`
});

Extend parent functions

When you need to reuse functions, of the parent you're extending, you can avoid writing something like this in any function:

domc.getType('parent-type').model.prototype.init.apply(this, arguments);

by using extendFn and extendFnView arrays:

domc.addType('new-type', {
  extend: 'parent-type',
  extendFn: ['init'], // array of model functions to extend
  model: {
    init() {
      // do something;
    },
  }
});

The same would be for the view by using extendFnView

Lifecycle Hooks

Each component triggers different lifecycle hooks, which allows you to add custom actions at their specific stages. We can distinguish 2 different types of hooks: global and local. You define local hooks when you create/extend a component type (usually via some model/view method) and the reason is to react to an event of that particular component type. Instead, the global one, will be called indistinctly on any component (you listen to them via editor.on) and you can make use of them for a more generic use case or also listen to them inside other components.

Let's see below the flow of all hooks:

• Local hook: model.init() method, executed once the model of the component is initiliazed
• Global hook: component:create event, called right after model.init(). The model is passed as an argument to the callback function. Es. editor.on('component:create', model => console.log('created', model))
• Local hook: view.init() method, executed once the view of the component is initiliazed
• Local hook: view.onRender() method, executed once the component is rendered on the canvas
• Global hook: component:mount event, called right after view.onRender(). The model is passed as an argument to the callback function.
• Local hook: model.updated() method, executes when some property of the model is updated.
• Global hook: component:update event, called after model.updated(). The model is passed as an argument to the callback function. You can also listen to specific property change via component:update:{propertyName}
• Local hook: model.removed() method, executed when the component is removed.
• Global hook: component:remove event, called after model.removed(). The model is passed as an argument to the callback function.

Below you can find an example usage of all the hooks

editor.DomComponents.addType('test-component', {
  model: {
    defaults: {
      testprop: 1,
    },
    init() {
      console.log('Local hook: model.init');
      this.listenTo(this, 'change:testprop', this.handlePropChange);
      // Here we can listen global hooks with editor.on('...')
    },
    updated(property, value, prevValue) {
      console.log('Local hook: model.updated',
        'property', property, 'value', value, 'prevValue', prevValue);
    },
    removed() {
      console.log('Local hook: model.removed');
    },
    handlePropChange() {
      console.log('The value of testprop', this.get('testprop'));
    }
  },
  view: {
    init() {
      console.log('Local hook: view.init');
    },
    onRender() {
      console.log('Local hook: view.onRender');
    },
  },
});

// A block for the custom component
editor.BlockManager.add('test-component', {
  label: 'Test Component',
  content: '<div data-gjs-type="test-component">Test Component</div>',
});

// Global hooks
editor.on(`component:create`, model => console.log('Global hook: component:create', model.get('type')));
editor.on(`component:mount`, model => console.log('Global hook: component:mount', model.get('type')));
editor.on(`component:update:testprop`, model => console.log('Global hook: component:update:testprop', model.get('type')));
editor.on(`component:remove`, model => console.log('Global hook: component:remove', model.get('type')));

Components & JS

If you want to know how to create Components with javascript attached (eg. counters, galleries, slideshows, etc.) check the dedicated page Components & JS

Hints

<div id="gjs">
 ...
 <cutom-element></cutom-element>
 ...
</div>

<script>
 var editor = grapesjs.init({
      container : '#gjs',
      fromElement: true,
  });

  editor.DomComponents.addType('cutom-element-type', {...});
</script>

In the example above the editor will not get the new type from the HTML because the content is already parsed and appended, so it'll get it only with new components (eg. from Blocks)

Solution 1: turn off autorender

<script>
 var editor = grapesjs.init({
      autorender: 0,
      container : '#gjs',
      fromElement: true,
  });

  editor.DomComponents.addType('cutom-element-type', {...});

  // after all new types
  editor.render();
</script>

Solution 2: put all the stuff inside a plugin (Creating plugins)