javascript - 重构 JS 函数以定位多个 id

Question

我在页面上有四个框，我想在用户单击它们时更改颜色。我给每个盒子一个 id:

<div id="boxa" onclick="changeColorA()"></div>
<div id="boxb" onclick="changeColorB()"></div>
<div id="boxc" onclick="changeColorC()"></div>
<div id="boxd" onclick="changeColorD()"></div>

如您所见，为了使用 onclick 更改框颜色，我必须为每个框编写一个单独的函数:

function changeColorA() {
  var col = '#'+Math.floor(Math.random()*16777215).toString(16);
  document.getElementById("boxa").style.backgroundColor=col;
}

function changeColorB() {
  var col = '#'+Math.floor(Math.random()*16777215).toString(16);
  document.getElementById("boxb").style.backgroundColor=col;
}

function changeColorC() {
  var col = '#'+Math.floor(Math.random()*16777215).toString(16);
  document.getElementById("boxc").style.backgroundColor=col;
}

function changeColorD() {
  var col = '#'+Math.floor(Math.random()*16777215).toString(16);
  document.getElementById("boxd").style.backgroundColor=col;
} 

我在 iPad 上的浏览​​器中运行了它，但运行速度太慢。我如何重构它，以便我只有一个函数可以针对用户点击的任何框？

function changeColorA() {
  var col = '#' + Math.floor(Math.random() * 16777215).toString(16);
  document.getElementById("boxa").style.backgroundColor = col;
}

function changeColorB() {
  var col = '#' + Math.floor(Math.random() * 16777215).toString(16);
  document.getElementById("boxb").style.backgroundColor = col;
}

function changeColorC() {
  var col = '#' + Math.floor(Math.random() * 16777215).toString(16);
  document.getElementById("boxc").style.backgroundColor = col;
}

function changeColorD() {
  var col = '#' + Math.floor(Math.random() * 16777215).toString(16);
  document.getElementById("boxd").style.backgroundColor = col;
}

body {
  margin: 10px;
  width: 758px;
  height: 1014px;
}

#main {
  background-color: #00b894;
  width: 748px;
  height: 1004px;
}

.container-1 {
  text-align: center;
}

.container-2 {
  text-align: center;
}

#boxa {
  margin-top: 250px;
  margin-right: 20px;
  width: 200px;
  height: 200px;
  background-color: #fab1a0;
  border-radius: 20px;
  display: inline-block;
}

#boxb {
  width: 200px;
  height: 200px;
  background-color: #00cec9;
  border-radius: 20px;
  display: inline-block;
}

#boxc {
  margin-top: 20px;
  margin-right: 20px;
  width: 200px;
  height: 200px;
  background-color: #55efc4;
  border-radius: 20px;
  display: inline-block;
}

#boxd {
  width: 200px;
  height: 200px;
  background-color: #6c5ce7;
  border-radius: 20px;
  display: inline-block;
}

<div id="boxa" onclick="changeColorA()"></div>
<div id="boxb" onclick="changeColorB()"></div>
<div id="boxc" onclick="changeColorC()"></div>
<div id="boxd" onclick="changeColorD()"></div>

代码笔:https://codepen.io/simonrevill/pen/WzZReX

Answer 1

您可以使用 addEventListener() 方法为附加事件监听器分配一个公共(public)类。在事件监听器中 this 指的是调用事件处理程序的元素

function changeColor() {
  var col = '#' + Math.floor(Math.random() * 16777215).toString(16);
  this.style.backgroundColor = col;
}

var boxes = document.querySelectorAll('.box');
for (var i = 0; i < boxes.length; i++)
  boxes[i].addEventListener('click', changeColor)

body {
  margin: 10px;
  width: 758px;
  height: 1014px;
}

#main {
  background-color: #00b894;
  width: 748px;
  height: 1004px;
}

.container-1 {
  text-align: center;
}

.container-2 {
  text-align: center;
}

#boxa {
  margin-top: 250px;
  margin-right: 20px;
  width: 200px;
  height: 200px;
  background-color: #fab1a0;
  border-radius: 20px;
  display: inline-block;
}

#boxb {
  width: 200px;
  height: 200px;
  background-color: #00cec9;
  border-radius: 20px;
  display: inline-block;
}

#boxc {
  margin-top: 20px;
  margin-right: 20px;
  width: 200px;
  height: 200px;
  background-color: #55efc4;
  border-radius: 20px;
  display: inline-block;
}

#boxd {
  width: 200px;
  height: 200px;
  background-color: #6c5ce7;
  border-radius: 20px;
  display: inline-block;
}

<div class="box" id="boxa"></div>
<div class="box" id="boxb"></div>
<div class="box" id="boxc"></div>
<div class="box" id="boxd"></div>

引用文献

1. EventTarget.addEventListener()
2. document.querySelectorAll()