React Breakpoints Mixin

BreakpointsMixin for your React Components.

Example

See the working example page.

Install

The package is available through npm and also bower.

npm

npm install --save react-breakpoints-mixin

bower

bower install --save react-breakpoints-mixin

Import

The BreakpointsMixin module is packaged in the UMD format, which means you can bring it in as a CommonJS module using require, or as a global variable using a <script> tag.

CommonJS

var BreakpointsMixin = require('react-breakpoints-mixin').BreakpointsMixin;

The export has a BreakpointsMixin property which you can assign to a variable.

Global Variable

  <script src="bower_components/react-breakpoints-mixin/dist/react-breakpoints-mixin.js"></script>

The script exposes a BreakpointsMixin global variable.

Use

Once you have imported the BreakpointsMixin variable, you need to ...

1. Add it to your fancy component's list of mixins.
2. Define breakpoints for width and/or height.
3. Generate css classes using the provided this.breakpointsClasses() method.

var FancyComponent = React.createClass({
 
  mixins: [ BreakpointsMixin ], /* [1] */
 
  breakpoints: { /* [2] */
    width: {
      "small": [0, 400],
      "medium": [400, 600],
      "large": [600, Infinity]
    },
    height: {
      "short": [0, 100],
      "medium": [100, 200],
      "long": [200, Infinity]
    }
  },
 
  render: function () {
    <div className={this.getClasses()}>Hello World</div>
  },
 
  getClasses: function () {
    return React.addons.classSet(this.breakpointsClasses('fancy-component')); /* [3] */
  }
 
});

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NOTE: To use React.addons.classSet you will need to include react with addons.

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Defining Breakpoints

Breakpoints are defined by adding a breakpoints property to your component.

The breakpoints property is an object whose keys are element properties that the breakpoints are evaluated against. Only width and height are supported.

Under each property is another object, whose keys are the user-defined names for the breakpoints and the value is the breakpoint range, an array with two integer values representing the min and max of the breakpoint.

To avoid having to subtract one pixel between breakpoints, the max is not included in range comparisons during breakpoint evaluation. The comparison to see if a breakpoint matches effectively looks like this:

min <= width && width < max

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NOTE: We have deemed overlapping breakpoints to be a thing of naught. A warning will be output to the console if overlapping breakpoints are detected.

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Reference

BreakpointsMixin

Type: Object

The main module, a mixin for use with React.

this.breakpointsClasses( className )

Type: Method

Params:

• className, Type: String

Return Type: Object

Generates BEM modifier classes for each matched breakpoint. Returns an object to be passed to React.addons.classSet.

This method satisfies the typical use case of applying styles based on the element's dimensions through the use of modifier classes.

These classes follow the format of:

{className}--{property}-{name}

Where className is passed in as argument, property is the property the breakpoint is defined against (width, height), and name is the name defined in the breakpoints definition on your component.

For example, given the following breakpoints:

  breakpoints: {
    width: {
      "small": [0, 400],
      "medium": [400, 600],
      "large": [600, Infinity]
    },
    height: {
      "short": [0, 100],
      "medium": [100, 200],
      "long": [200, Infinity]
    }
  },

Calling this.breakpointsClasses('responsive-colors'), with the element width equal to 300 pixels, and the element height equal to 50 pixels, would return something like:

{
  "responsive-colors": true,
  "responsive-colors--width-medium": true,
  "responsive-colors--height-short": true
}

this.breakpointMatched( property, name )

Type: Method

Params:

• property, Type: String
• name, Type: String

Return Type: Bool

Checks to see if a defined breakpoint has been matched. Returns a boolean.

When modifier classes are insufficient, this method can be used, typically in the render method, or the render process, to check if a breakpoint is matched. Use this method sparingly. For most cases modifier classes should be enough.

For example, to check if a breakpoint on width named small is matched, call the method like so:

  var matched = this.breakpointMatched('width', 'small');

this.breakpointsEvaluate()

Type: Method

Evaluates breakpoints. Called in componentDidMount and on window resize.

This method can also be called on the component to force evaluation of breakpoints in a scenario where the element dimensions may have changed, but the component has already been mounted and the window is not resized. An example of this scenario could be a user interface with resizeable panels.

This method compares the element properties (width or height) with the corresponding breakpoints and records the matched breakpoints in the component state, which results in another component render.

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NOTE: Consider the breakpoints state private and read only. Use this.breakpointsClasses(className) or this.breakpointMatched(property, name) to glean information about state.

NOTE: There are a few techniques for detecting resize on elements, independent of window resize, such as listening to scroll event on a nested div, or resize in an invisible <iframe>, but we found they impact performance to an unacceptable degree, especially on pages that have many components using the BreakpointsMixin. We settled with evaluating breakpoints only in componentDidMount and on window resize and exposing this.breakpointsEvaluate() for those rare cases it is needed.

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