How to access custom attributes from event object in React?

event.target gives you the native DOM node, then you need to use the regular DOM APIs to access attributes. Here are docs on how to do that:Using data attributes.

You can do either event.target.dataset.tag or event.target.getAttribute('data-tag'); either one works.

<div className='btn' onClick={(e) =>
     console.log(e.currentTarget.attributes['tag'].value)}
     tag='bold'>
    <i className='fa fa-bold' />
</div>

so e.currentTarget.attributes['tag'].value works for me

As of React v16.1.1 (2017), here is the official solution: https://reactjs.org/docs/handling-events.html#passing-arguments-to-event-handlers

TLDR: OP should do:

render: function() {
...
<a style={showStyle} onClick={(e) => this.removeTag(i, e)}></a>
...
removeTag: function(i, event) {
    this.setState({inputVal: i}); 
}

This single line of code solved the problem for me:

event.currentTarget.getAttribute('data-tag')

You can access data attributes something like this

event.target.dataset.tag

If anyone is trying to use event.target in React and finding a null value, it is because a SyntheticEvent has replaced the event.target. The SyntheticEvent now holds 'currentTarget', such as in event.currentTarget.getAttribute('data-username').

https://facebook.github.io/react/docs/events.html

It looks like React does this so that it works across more browsers. You can access the old properties through a nativeEvent attribute.

You can simply use event.target.dataset object . This will give you the object with all data attributes.

Try instead of assigning dom properties (which is slow) just pass your value as a parameter to function that actually create your handler:

render: function() {
...
<a style={showStyle} onClick={this.removeTag(i)}></a>
...
removeTag = (customAttribute) => (event) => {
    this.setState({inputVal: customAttribute});
}

I think it's recommended to bind all methods where you need to use this.setState method which is defined in the React.Component class, inside the constructor, in your case you constructor should be like

    constructor() {
        super()
        //This binding removeTag is necessary to make `this` work in the callback
        this.removeTag = this.removeTag.bind(this)
    }
    removeTag(event){
        console.log(event.target)
        //use Object destructuring to fetch all element values''
        const {style, dataset} = event.target
        console.log(style)
        console.log(dataset.tag)
    }
   render() {
   ...
      <a data-tag={i} style={showStyle} onClick={this.removeTag.bind(null, i)}></a>
   ...},

For more reference on Object destructuring https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Destructuring_assignment#Object_destructuring

This worked for me... My attribute is named "attr" in the example.

e.target.selectedOptions[0].attributes.attr.value

If you have multiple icons with different data-label (age,name,email):

       <button
          data-label="name" 
          onMouseOver={handleValue}
          className="icon"
        >
          <FaUser />
        </button>

when the mouse is over an icon, you change the title by accessing data-label

const handleValue = (e) => {
    // making sure mouse is over an icon
    if (e.target.classList.contains("icon")) {
      const newValue = e.target.dataset.label;
      setTitle(newValue);
      setValue(person[newValue]);
    }
  };