use

$(window).width()

or

$(document).width()

or

$('body').width()

use

$(window).width()

or

$(document).width()

or

$('body').width()

我知道现在回答这个问题有点晚了，但我希望这对有类似问题的人有所帮助。当页面因任何原因刷新时，它也可以工作。

$(document).ready(function(){

if ($(window).width() < 960 && $(window).load()) {
        $("#up").hide();
    }

    if($(window).load()){
        if ($(window).width() < 960) {
        $("#up").hide();
        }
    }

$(window).resize(function() {
    if ($(window).width() < 960 && $(window).load()) {
        $("#up").hide();
    }
    else{
        $("#up").show();
    }

    if($(window).load()){
        if ($(window).width() < 960) {
        $("#up").hide();
        }
    }
    else{
        $("#up").show();
    }

});});

使用jQuery获取窗口的宽度。

if ($(window).width() < 960) {
   alert('Less than 960');
}
else {
   alert('More than 960');
}

简单干净的解决方案使用香草JavaScript

let app = document.getElementById('app') const changeColorFn = ( app, color ) => { app.setAttribute("style",`background: ${color}`) } const winSizeFn = ( winWidth, callback, app, color ) => { if (window.innerWidth < winWidth ) { callback(app, color); } } winSizeFn( '1200', changeColorFn, app, 'red' ) winSizeFn( '800', changeColorFn, app, 'green' ) winSizeFn( '500', changeColorFn, app, 'blue' ) window.addEventListener("resize", (e) => { // add winSizeFn here if you want call function on window resize }) <div id="app">My app content</div>

// Adds and removes body class depending on screen width.
function screenClass() {
    if($(window).innerWidth() > 960) {
        $('body').addClass('big-screen').removeClass('small-screen');
    } else {
        $('body').addClass('small-screen').removeClass('big-screen');
    }
}

// Fire.
screenClass();

// And recheck when window gets resized.
$(window).bind('resize',function(){
    screenClass();
});