最近写了一个原生JavaScript实现矩形块大小任意缩放的案例，感觉里面的东西比较的绕，这里分享源码给大家，一起学习一下。
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>原生JavaScript实现矩形块大小任意缩放</title>
</head>
<style>
* {
margin: 0;
padding: 0;
}
.box {
position: relative;
top: 200px;
left: 500px;
width: 500px;
height: 300px;
background-color: blueviolet;
}
.box>div:nth-child(-n+4) {
position: absolute;
width: 5px;
height: 5px;
background-color: #cc00ff;
}
.box>div:nth-child(n+5) {
position: absolute;
background-color: #f30497;
}
.box>.dot1 {
cursor: nw-resize;
top: -5px;
left: -5px;
}
.box>.dot2 {
cursor: ne-resize;
top: -5px;
right: -5px;
}
.box>.dot3 {
cursor: se-resize;
bottom: -5px;
right: -5px;
}
.box>.dot4 {
cursor: sw-resize;
bottom: -5px;
left: -5px;
}
.box>.line1,
.box>.line3 {
width: 500px;
height: 5px;
}
.box>.line1 {
top: -5px;
cursor: n-resize;
}
.box>.line3 {
bottom: -5px;
cursor: s-resize;
}
.box>.line2,
.box>.line4 {
width: 5px;
height: 300px;
}
.box>.line2 {
right: -5px;
cursor: e-resize;
}
.box>.line4 {
left: -5px;
cursor: e-resize;
}
</style>
<body>
<div class="box">
<div class="dot1"></div>
<div class="dot2"></div>
<div class="dot3"></div>
<div class="dot4"></div>
<div class="line1"></div>
<div class="line2"></div>
<div class="line3"></div>
<div class="line4"></div>
</div>
<script>
//获取相关元素节点
let box = document.querySelector(".box");
let dots = document.querySelectorAll(".box>div:nth-child(-n+4)");
let lines = document.querySelectorAll(".box>div:nth-child(n+5)");
// 类边框宽度
let bd = 5;
//for循环指定事件对象
function changeBox([box, dots, lines, bd]) {
for (let i = 0; i < 4; i++) {
let { 0: dot1, 1: dot2, 2: dot3, 3: dot4 } = dots; //dots对象解构
let { 0: line1, 1: line2, 2: line3, 3: line4 } = lines; //lines对象解构
//矩形顶点点击拖动调整大小
dots[i].onmousedown = function (ev) {
//点击事件初始化相关值
let oldY = ev.clientY; //顶点原本的y值
let oldX = ev.clientX; //顶点原本的x值
let h = box.clientHeight; //box的高度
let w = box.clientWidth; //box的宽度
let t = box.offsetTop; //box距离顶部的top值
let l = box.offsetLeft; //box距离左边的left值
window.onmousemove = function (e) {
let offsetY = e.clientY - oldY; //鼠标移动y轴偏移量
let offsetX = e.clientX - oldX; //鼠标移动x轴偏移量
//if条件是判断鼠标点击的节点目标对象
if (i == 0) {
box.style.height = `${h - offsetY + bd}px`; //box高度变化
box.style.top = `${t + offsetY - bd}px`; //box的top值变化(定位)
box.style.width = `${w - offsetX + bd}px`; //box的宽度变化
box.style.left = `${l + offsetX - bd}px`; //box的left值变化(定位)
} else if (i == 1) {
box.style.height = `${h - offsetY + bd}px`;
box.style.top = `${t + offsetY - bd}px`;
box.style.width = `${w + offsetX + bd}px`;
} else if (i == 2) {
box.style.height = `${h + offsetY + bd}px`;
box.style.width = `${w + offsetX + bd}px`;
} else if (i == 3) {
box.style.height = `${h + offsetY + bd}px`;
box.style.width = `${w - offsetX + bd}px`;
box.style.left = `${l + offsetX - bd}px`;
}
//边框线的高度/宽度随着box的大小变化而变化
line1.style.width = box.style.width;
line2.style.height = box.style.height;
line3.style.width = box.style.width;
line4.style.height = box.style.height;
}
}
//边框点击拖动调整大小
lines[i].onmousedown = function (ev) {
//点击事件初始化相关值
let oldY = ev.clientY; //顶点原本的y值
let oldX = ev.clientX; //顶点原本的x值
let h = box.clientHeight; //box的高度
let w = box.clientWidth; //box的宽度
let t = box.offsetTop; //box距离顶部的top值
let l = box.offsetLeft; //box距离左边的left值
window.onmousemove = function (e) {
let offsetX = e.clientX - oldX; //鼠标移动x轴偏移量
let offsetY = e.clientY - oldY; //鼠标移动y轴偏移量
//if条件是判断鼠标点击的节点目标对象
if (i == 0) {
box.style.height = `${h - offsetY + bd}px`;
box.style.top = `${t + offsetY - bd}px`;
} else if (i == 1) {
box.style.width = `${w + offsetX + bd}px`;
} else if (i == 2) {
box.style.height = `${h + offsetY + bd}px`;
} else {
box.style.width = `${w - offsetX + bd}px`;
box.style.left = `${l + offsetX - bd}px`;
}
//边框线的高度/宽度随着box的大小变化而变化
line1.style.width = box.style.width;
line2.style.height = box.style.height;
line3.style.width = box.style.width;
line4.style.height = box.style.height;
}
}
//鼠标抬起后清除鼠标移动事件
window.onmouseup = function () {
window.onmousemove = false;
}
}
}
changeBox([box, dots, lines, bd])
</script>
</body>
</html>
以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持。