module-match-height.js

Inspired by: jquery-match-height

matchHeight: makes the height of all selected elements exactly equal

Demo - Features - Install - Usage - Options - Data API
Advanced Usage - Changelog - License

Demo

See the module-match-height.js demo.

Modern browsers

In the years since this library was originally developed there have been updates to CSS that can now achieve equal heights in many situations. If you only need to support modern browsers then consider using CSS Flexbox and CSS Grid instead.

Best practice

Use this library to match height of internal elements, like title or text of teasers

Features

• match the heights for groups of elements automatically
• use the maximum height or define a specific target element
• anywhere on the page and anywhere in the DOM
• responsive (updates on window resize)
• row aware (handles floating elements and wrapping)
• accounts for box-sizing and mixed padding, margin, border values
• handles images and other media (updates after loading)
• easily removed when needed
• data attributes API
• tested in Edge, Chrome, Firefox

Install

CDN via jsDelivr

<script src="https://cdn.jsdelivr.net/npm/module-match-height@latest/dist/module-match-height.min.js" type="text/javascript"></script>

Download module-match-height.js and include the script in your HTML file:

<script src="module-match-height.js" type="text/javascript"></script>

You can also install using the package managers NPM.

npm install module-match-height

modular code

import MatchHeight from 'module-match-height'

Usage

new MatchHeight(document.body, {elements: '.item'});

const containers = document.querySelectorAll(".items-container");
containers.forEach((container) => {			
    new MatchHeight(document.body, {elements: '.item'});
});

Where options is an optional parameter.
See below for a description of the available options and defaults.

The above example will set all selected elements with the class item to the height of the tallest.
If the items are on multiple rows, the items of each row will be set to the tallest of that row (see byRow option).

Call this on the event (the plugin will automatically update on window load).
See the included test.html for many working examples.

Also see the Data API below for a simple, alternative inline usage.

Options

The default options are:

{
    elements: null,
    byRow: true,
    property: 'height',
    target: null,
    remove: null,
    attributeName: null,
    events: true,
    throttle: 80
}

Where:

• elements is an optional string containing one or more selectors to match against. This string must be a valid CSS selector string
• byRow is true or false to enable row detection
• property is the CSS property name to set (e.g. 'height' or 'min-height')
• target is an optional element to use instead of the element with maximum height
• remove is an optional element/s to excluded
• attributeName is an optional for use custom attribute
• events is true or false to enable default events
• throttle milliseconds to executed resize event, default is 80

Data API

Use the data attribute data-mh="group-name" or data-match-height="group-name" where group-name is an arbitrary string to identify which elements should be considered as a group.

<div data-mh="my-group">My text</div>
<div data-mh="my-group">Some other text</div>
<div data-mh="my-other-group">Even more text</div>
<div data-mh="my-other-group">The last bit of text</div>

All elements with the same group name will be set to the same height when the page is loaded, regardless of their position in the DOM, without any extra code required.

It's possible to use custom data attribute data-same-height="group-name"

<div data-same-height="my-group">My text</div>
<div data-same-height="my-group">Some other text</div>
<div data-same-height="my-other-group">Even more text</div>
<div data-same-height="my-other-group">The last bit of text</div>

const containers = document.querySelectorAll(".data-api-items");
containers.forEach((container) => {
    new MatchHeight(container, {attributeName: 'data-same-height'});
});

Note that byRow will be enabled when using the data API, if you don't want this (or require other options) then use the alternative method above.

Advanced Usage

There are some additional functions and properties you should know about:

Manually trigger an update

window.dispatchEvent(new Event('resize'));

If you need to manually trigger an update of all currently set groups, for example if you've modified some content.

Row detection

You can toggle row detection by setting the byRow option, which defaults to true.
It's also possible to use the row detection function at any time:

Custom target element

const containers = document.querySelectorAll(".target-items");
containers.forEach((container) => {			
    new MatchHeight(container, {elements: '.item-0, .item-2, .item-3', target: document.getElementById("target-item-1")});
});

Will set all selected elements to the height of the first item with class sidebar.

Custom property

const containers = document.querySelectorAll(".property-items");
containers.forEach((container) => {			
    new MatchHeight(container, {elements: '.item', property: 'min-height'});
});

This will set the min-height property instead of the height property.

Where event a event object (DOMContentLoaded, resize, orientationchange).

Throttling resize updates

By default, the events is throttled to execute at a maximum rate of once every 80ms. Decreasing the throttle option will update your layout quicker, appearing smoother during resize, at the expense of performance. If you experience lagging or freezing during resize, you should increase the throttle option.

Manually apply match height

Manual apply, code for JavaScript framework/library (e.g. vue, react ...).

var el = new MatchHeight(document.body, {elements: '.item'});
...
el._apply();
el._applyDataApi('data-match-height');
el._applyDataApi('data-mh');
el._applyAll();

Remove match height from elements

Reset inline style property

var el = new MatchHeight(document.body, {elements: '.item'});
...
el._remove();

Remove events from match height elements

Reset events

var el = new MatchHeight(document.body, {elements: '.item'});
...
el._unbind();

Known limitations

CSS transitions and animations are not supported

You should ensure that there are no transitions or other animations that will delay the height changes of the elements you are matching, including any transition: all rules. Otherwise the plugin will produce unexpected results, as animations can't be accounted for.

Vue3 Example:

import MatchHeight from 'module-match-height';
export default {
    name: 'Example',
    data: function () {
        return {
            matchHeight: new MatchHeight(document.body, {elements: '.item p'});
        }
    },
    beforeUnmount() {
        this.matchHeight._unbind();
    },
    mounted() {
        this.matchHeight._apply();
    },
    methods: {
        reMatch() {
            this.matchHeight._apply();
        }
    }
}

React Example:

import MatchHeight from 'module-match-height';
class MyComponent extends Component {
    matchHeight = new MatchHeight(document.body, {elements: '.item p'});
    componentDidMount() {
        this.matchHeight._apply();
    }
    componentWillUnmount() {
        this.matchHeight._unbind();
    }
    render() {
        return (
            ...
        );
    }
}

Not duplicate instance!

I suggest to assign element to a variable for not create multiple instances and events

//Right solution
var el = new MatchHeight(document.body, {elements: '.item'});
... json update
el._apply();

//Wrong solution
new MatchHeight(document.body, {elements: '.item'});
... json update
new MatchHeight(document.body, {elements: '.item'})._apply();

Changelog

To see what's new or changed in the latest version, see the changelog

License

module-match-height.js is licensed under The MIT License (MIT) Copyright (c) 2023 Simone Miterangelis

This license is also supplied with the release and source code. As stated in the license, absolutely no warranty is provided.