javascript - 如何在DIV宽度改变时动态改变类？

Question

我知道如何在窗口大小更改时使用 Jquery 更改类，但我需要它基于 DIV 的宽度，并在 DIV 宽度更改时动态更改。

$(window).resize(function() {

   var wrapWidth = $('.info-wrap').width();

    if (wrapWidth >= 500) {

      $('#partOne').addClass('big');
      $('#partTwo').addClass('big');

    } else {

      $('#partOne').removeClass('big');
      $('#partTwo').removeClass('big');
    }
});

这在窗口大小改变时起作用。但是，我可以使用什么来代替 $(window).resize 来获取 DIV 变化时的宽度？

Answer 1

这是观察元素属性的示例。

参见:MutationObserver和 Mutation Events

CSS

#watch {
    border: 1px solid;
}

HTML

<button id="button">Click me</button>
<div id="watch" style="width: 100px; height: 50px;"></div>

Javascript

/*jslint sub: true, maxerr: 50, indent: 4, browser: true */
/* global global */

(function (global) {
    "use strict";

    if (typeof global.MutationObserver !== "function") {
        global.MutationObserver = global.WebKitMutationObserver || global.MozMutationObserver;
    }

    var watch = document.getElementById("watch");

    function whenClicked() {
        watch.style.width = "200px";
    }

    document.getElementById("button").addEventListener("click", whenClicked, false);

    if (typeof global.MutationObserver !== "function") {
        // chrome doesn't despatch an event for "DOMAttrModified"
        watch.addEventListener("DOMAttrModified", function (evt) {
            console.log("Attribute changed", evt.target);
        }, false);
    } else {
        var observer = new global.MutationObserver(function (mutations) {
            mutations.forEach(function (mutation) {
                if (mutation.type === 'attributes') {
                    console.log("Attribute changed", mutation);
                }
            });
        });

        observer.observe(watch, {
            attributes: true,
            childList: true,
            characterData: true,
            subtree: true
        });
    }
}(window));

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