思路：采用flex布局，js即时修改固定列的宽度
注意：父元素需设置position:relative；因offsetLeft和offsetTop是相对于具有定位的（position:absolute或者position：relative）父级元素的距离
html：
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <meta http-equiv="X-UA-Compatible" content="ie=edge"> <title>Document</title> <link rel="stylesheet" href="./index.css"> <link rel="stylesheet" href="https://cdn.staticfile.org/font-awesome/4.7.0/css/font-awesome.css"> <script src="./index.js"></script> </head> <body> <div id="box"> <div id="left"> </div> <div id="line"> <a id="line1"> <span><i class="fa fa-caret-right"></i></span> </a> </div> <div id="right"> </div> </div> </body> </html>
css：
body { font: 14px/1.5 Arial; color: #666; } #box { position: relative; width: 600px; height: 400px; border: 2px solid #000; margin: 10px auto; overflow: hidden; display: flex; } #left { height: 100%; flex: 1; overflow: hidden; } #right { width: 300px; overflow: hidden; } #line { width: 8px; background: lightblue; cursor: col-resize; } #line a{ cursor: pointer; text-align: center; }
js：
function $(id) { return document.getElementById(id) } window.onload = function () { var oBox = $("box"), oLeft = $("left"), oRight = $("right"), oLine = $("line"), oLine1 = $("line1"); var flag = true; var wid = 0; oLine.onmousedown = function (e) { var disX = (e || event).clientX; var owidth = oBox.clientWidth - oLine.offsetLeft; document.onmousemove = function (e) { var iT = owidth - ((e || event).clientX - disX); var e = e || window.event; var maxT = oBox.clientWidth - oLine.offsetWidth; oLine.style.margin = 0; iT < 30 && (iT = 30); iT > maxT && (iT = maxT); wid = iT; oRight.style.width = iT + "px"; return false }; document.onmouseup = function () { document.onmousemove = null; document.onmouseup = null; oLine.releaseCapture && oLine.releaseCapture() }; oLine.setCapture && oLine.setCapture(); return false }; oLine1.onclick = function () { if (flag) { oRight.style.width = 30 + "px"; flag = false; } else { if (wid && wid > 30) { oRight.style.width = wid + "px"; } else { oRight.style.width = 300 + "px"; } flag = true; } } };
效果如下：