javascript - 使用 event.currentTarget 获取 child 的索引

Question

这里如何去除 jQuery 的“.index()”？我正在寻找的是一种获取单击按钮索引的 native 方法，请参阅下面的源代码(完美运行但我真的找不到任何 Vanilla-JS 解决方案，我不想为此使用 jQuery一个小任务)。谢谢。

    function navButtonClick(ev) {
        var buttonIndex = $(ev.currentTarget).index(); /* How to get rid of jQuery? */

        document.getElementById("output").innerHTML = buttonIndex;
    }

    function startTemplate() {
        var i;
        var navItems = document.querySelectorAll("#navigation button");

        for (i=0; i < navItems.length; i++) {
            navItems[i].addEventListener("click", navButtonClick);
        }
    }

    document.addEventListener("DOMContentLoaded", startTemplate);
    

The HTML part looks like this:

    <nav id="navigation" role="navigation">
        <button type="button"> <em>Navi tab 1</em> </button>
        <button type="button"> Navi tab 2 </button>
        <button type="button"> Navi tab 3 </button>
        <button type="button"> Navi tab 4 </button>
    </nav>

    <div id="output"></div>

Answer 1

你可以这样做:

function navButtonClick(ev) {
    var buttonIndex = Array.prototype.indexOf.call(this.parentElement.children, this);

    document.getElementById("output").innerHTML = buttonIndex;
}

function startTemplate() {
    var i;
    var navItems = document.querySelectorAll("#navigation button");

    for (i=0; i < navItems.length; i++) {
        navItems[i].addEventListener("click", navButtonClick);
    }
}

document.addEventListener("DOMContentLoaded", startTemplate);

检查下面的片段:

function navButtonClick(ev) {
  var buttonIndex = Array.prototype.indexOf.call(this.parentElement.children, this);

  document.getElementById("output").innerHTML = buttonIndex;
}

function startTemplate() {
  var i;
  var navItems = document.querySelectorAll("#navigation button");

  for (i = 0; i < navItems.length; i++) {
    navItems[i].addEventListener("click", navButtonClick);
  }
}

document.addEventListener("DOMContentLoaded", startTemplate);

<nav id="navigation" role="navigation">
  <button type="button"> <em>Navi tab 1</em> 
  </button>
  <button type="button">Navi tab 2</button>
  <button type="button">Navi tab 3</button>
  <button type="button">Navi tab 4</button>
</nav>

<div id="output"></div>