I do not know about React, but in the general case you can pass custom attributes like this:

1) define inside an html-tag a new attribute with data- prefix

data-mydatafield = "asdasdasdaad"

2) get from javascript with

e.target.attributes.getNamedItem("data-mydatafield").value 

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});
}

You can access data attributes something like this

event.target.dataset.tag

// Method inside the component
userClick(event){
 let tag = event.currentTarget.dataset.tag;
 console.log(tag); // should return Tagvalue
}
// when render element
<a data-tag="TagValue" onClick={this.userClick}>Click me</a>

或者您可以使用闭包：

render: function() {
...
<a data-tag={i} style={showStyle} onClick={this.removeTag(i)}></a>
...
},
removeTag: function (i) {
    return function (e) {
    // and you get both `i` and the event `e`
    }.bind(this) //important to bind function 
}

从React v16.1.1（2017）开始，以下是官方解决方案：https ://reactjs.org/docs/handling-events.html#passing-arguments-to-event-handlers

TLDR： OP应该做到：

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

为了帮助您以与您要求不同的方式获得期望的结果：

render: function() {
    ...
    <a data-tag={i} style={showStyle} onClick={this.removeTag.bind(null, i)}></a>
    ...
},
removeTag: function(i) {
    // do whatever
},

请注意bind()。因为这全部是JavaScript，所以您可以做这样的方便的事情。我们不再需要将数据附加到DOM节点来跟踪它们。

IMO这比依赖DOM事件干净得多。

2017年4月更新：这些天我会写onClick={() => this.removeTag(i)}而不是.bind