Set & Get HTML Data Attributes In Javascript (Simple Examples)

Welcome to a quick tutorial on how to set and get HTML data attributes in Javascript. Want to insert your own custom property or data into HTML elements?

That covers the basics, but read on for more examples!

 

 

TLDR – QUICK SLIDES

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TABLE OF CONTENTS

 

 

 

1) SET DATA ATTRIBUTE

<!-- (A) SET DATA ATTRIBUTE IN HTML START TAG -->
<div id="demoA" data-color="red">
  This element has custom data attributes.
</div>
 
<!-- (B) SET DATA ATTRIBUTE IN JAVASCRIPT -->
<script>
document.getElementById("demoA").dataset.priority = "high";
// <div id="demoA" data-color="red" data-priority="high">
</script>

As in the introduction above, there are 2 ways to set HTML data attributes:

1. Directly in the HTML start tag itself data-KEY="VALUE".
2. Using Javascript ELEMENT.dataset.KEY = "VALUE".

Yes, we can have multiple data attributes attached to a single element.

 

2) GET DATA ATTRIBUTE

<!-- (A) ELEMENT WITH DATA ATTRIBUTES -->
<div id="demoB" data-color="red" data-priority="high">
  This element has custom data attributes.
</div>
 
<!-- (B) GET DATA ATTRIBUTE IN JAVASCRIPT -->
<script>
var el = document.getElementById("demoB");
console.log(el.dataset.color); // red
console.log(el.dataset.priority); // high
</script>

This one is as straightforward as can be. We can also retrieve the data using the same ELEMENT.dataset.KEY.

 

 

3) SET ARRAYS INTO DATA ATTRIBUTE

<!-- (A) DUMMY ELEMENT -->
<div id="demoC">Dummy</div>
 
<!-- (B) JAVASCRIPT -->
<script>
// (B1) GET HTML ELEMENT
var el = document.getElementById("demoC");

// (B2) SET ARRAY TO DATA ATTRIBUTE
// dataset can only be string - json.stringify() to turn array to string
el.dataset.array = JSON.stringify(["Red", "Green", "Blue"]);
 
// (B3) GET ARRAY BACK FROM STRING
// use json.parse() to turn encoded string back to array
console.log(JSON.parse(el.dataset.array));
</script>

A quick note, HTML data attributes must be a string and will not accept arrays/objects.

• To set an array into the data attribute, we use JSON.stringify() to encode the array into a string first.
• To retrieve the data, we use JSON.parse() to turn the string back into an array.

 

4) STORE HTML SNIPPETS IN DATA ATTRIBUTE

<!-- (A) DUMMY ELEMENTS -->
<div id="demoD" data-snippet="<strong>Foo</strong>">Demo D</div>
<div id="demoE">Demo E</div>

<!-- (B) JAVASCRIPT -->
<script>
// (B1) GET HTML SNIPPET
var snippet = document.getElementById("demoD").dataset.snippet;
 
// (B2) SET HTML SNIPPET
document.getElementById("demoE").innerHTML = snippet;
</script>

Yes, we can set an HTML snippet into data attributes… But the question is, why? If you want to use it as an HTML template, <template> is better for performance and it makes more sense.

 

 

5) SET CSS STYLE BASED ON DATA ATTRIBUTE

<!-- (A) CSS STYLES -->
<style>
div[data-color="red"] { background: red; }
div[data-color="green"] { background: green; }
div[data-color="blue"] { background: blue; }
</style>

<!-- (B) DUMMY ELEMENT -->
<div id="demoF">Dummy</div>
 
<!-- (C) JAVASCRIPT SET COLOR -->
<script>
function setColor (col) {
  document.getElementById("demoF").dataset.color = col;
}
</script>
<input type="button" value="Red" onclick="setColor('red')">
<input type="button" value="Green" onclick="setColor('green')">
<input type="button" value="Blue" onclick="setColor('blue')">

This final example is an extra bit to demonstrate how CSS can also be used to target different data attributes – Kind of useful, but I personally still prefer to stick with CSS classes and variables.

 

 

 

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EXAMPLE CODE DOWNLOAD

Click here for the source code on GitHub gist, just click on “download zip” or do a git clone. I have released it under the MIT license, so feel free to build on top of it or use it in your own project.

 

 

COMPATIBILITY CHECK

• Dataset – CanIUse

Data attributes are already well-supported in almost every browser.

 

LINKS & REFERENCES

• Using Data Attributes – MDN
• HTMLElement.dataset – MDN
• How to Use HTML5 Data Attributes – Sitepoint
• [attribute] – CSS-Tricks
• Working With JSON – MDN

 

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