// querySelector() 返回匹配到的第一个元素
var item = document.querySelector('.item');
console.log(item);// querySelectorAll() 返回匹配到的所有元素，是一个nodeList集合
var items = document.querySelectorAll('.item');
console.log(items[0]);

// 原生js
document.getElementById('btn').addEventListener('click', function (event) {event = event || window.event；if (event.preventDefault){// w3c方法 阻止默认行为
        event.preventDefault();} else{// ie 阻止默认行为event.returnValue = false;}
}, false);// jQuery
$('#btn').on('click', function (event) {event.preventDefault();
});

// 原生js
document.getElementById('btn').addEventListener('click', function (event) {event = event || window.event；if (event.stopPropagation){// w3c方法 阻止冒泡
        event.stopPropagation();} else{// ie 阻止冒泡event.cancelBubble = true;}
}, false);// jQuery
$('#btn').on('click', function (event) {event.stopPropagation();
});

$('#content').on("mousewheel DOMMouseScroll", function (event) { // chrome & ie || // firefoxvar delta = (event.originalEvent.wheelDelta && (event.originalEvent.wheelDelta > 0 ? 1 : -1)) || (event.originalEvent.detail && (event.originalEvent.detail > 0 ? -1 : 1));  if (delta > 0) { // 向上滚动console.log('mousewheel top');} else if (delta < 0) {// 向下滚动console.log('mousewheel bottom');}
});

function isSupportSVG() { var SVG_NS = 'http://www.w3.org/2000/svg';return !!document.createElementNS &&!!document.createElementNS(SVG_NS, 'svg').createSVGRect;
} // 测试
console.log(isSupportSVG());

function isSupportCanvas() {if(document.createElement('canvas').getContext){return true;}else{return false;}
}// 测试，打开谷歌浏览器控制台查看结果
console.log(isSupportCanvas());

function isWeiXinClient() {var ua = navigator.userAgent.toLowerCase(); if (ua.match(/MicroMessenger/i)=="micromessenger") { return true; } else { return false; }
}// 测试
alert(isWeiXinClient());

$('#myImage').click(function(event){//获取鼠标在图片上的坐标 console.log('X：' + event.offsetX+'\n Y:' + event.offsetY); //获取元素相对于页面的坐标 console.log('X：'+$(this).offset().left+'\n Y:'+$(this).offset().top);
});

<!-- dom -->
<input id="send" type="button" value="发送验证码">

// 原生js版本
var times = 60, // 临时设为60秒timer = null;document.getElementById('send').onclick = function () {// 计时开始timer = setInterval(function () {times--;if (times <= 0) {send.value = '发送验证码';clearInterval(timer);send.disabled = false;times = 60;} else {send.value = times + '秒后重试';send.disabled = true;}}, 1000);
}

// jQuery版本
var times = 60,timer = null;$('#send').on('click', function () {var $this = $(this);// 计时开始timer = setInterval(function () {times--;if (times <= 0) {$this.val('发送验证码');clearInterval(timer);$this.attr('disabled', false);times = 60;} else {$this.val(times + '秒后重试');$this.attr('disabled', true);}}, 1000);
});

//匹配字母、数字、中文字符 /^([A-Za-z0-9]|[\u4e00-\u9fa5])*$///验证邮箱 /^\w+@([0-9a-zA-Z]+[.])+[a-z]{2,4}$///验证手机号 /^1[3|5|8|7]\d{9}$///验证URL /^http:\/\/.+\.///验证身份证号码 /(^\d{15}$)|(^\d{17}([0-9]|X|x)$)///匹配中文字符的正则表达式 /[\u4e00-\u9fa5]///匹配双字节字符(包括汉字在内) /[^\x00-\xff]/

function formatDate(now) { var y = now.getFullYear();var m = now.getMonth() + 1; // 注意js里的月要加1 var d = now.getDate();var h = now.getHours(); var m = now.getMinutes(); var s = now.getSeconds();return y + "-" + m + "-" + d + " " + h + ":" + m + ":" + s;
} var nowDate = new Date(2016, 5, 13, 19, 18, 30, 20);console.log(nowDate.getTime()); // 获得当前毫秒数: 1465816710020
console.log(formatDate(nowDate));

<input id="txt" type="text">

//字符串截取
function getByteVal(val, max) {var returnValue = '';var byteValLen = 0;for (var i = 0; i < val.length; i++) {if (val[i].match(/[^\x00-\xff]/ig) != null) byteValLen += 2; else byteValLen += 1;if (byteValLen > max) break;returnValue += val[i];}return returnValue;
}$('#txt').on('keyup', function () {var val = this.value;if (val.replace(/[^\x00-\xff]/g, "**").length > 14) {this.value = getByteVal(val, 14);}
});

var browser = { versions: function() { var u = navigator.userAgent; return { trident: u.indexOf('Trident') > -1, //IE内核 presto: u.indexOf('Presto') > -1, //opera内核 webKit: u.indexOf('AppleWebKit') > -1, //苹果、谷歌内核 gecko: u.indexOf('Firefox') > -1, //火狐内核Gecko mobile: !!u.match(/AppleWebKit.*Mobile.*/), //是否为移动终端 ios: !!u.match(/\(i[^;]+;( U;)? CPU.+Mac OS X/), //ios android: u.indexOf('Android') > -1 || u.indexOf('Linux') > -1, //android iPhone: u.indexOf('iPhone') > -1 , //iPhone iPad: u.indexOf('iPad') > -1, //iPad webApp: u.indexOf('Safari') > -1 //Safari
        }; }
} if (browser.versions.mobile() || browser.versions.ios() || browser.versions.android() || browser.versions.iPhone() || browser.versions.iPad()) { alert('移动端');
}

//它返回一个对象，其中包含了left、right、top、bottom四个属性
var myDiv = document.getElementById('myDiv');
var x = myDiv.getBoundingClientRect().left;
var y = myDiv.getBoundingClientRect().top; // 相当于jquery的： $(this).offset().left、$(this).offset().top // js的：this.offsetLeft、this.offsetTop

function fullscreen(element) {if (element.requestFullscreen) {element.requestFullscreen();} else if (element.mozRequestFullScreen) {element.mozRequestFullScreen();} else if (element.webkitRequestFullscreen) {element.webkitRequestFullscreen();} else if (element.msRequestFullscreen) {element.msRequestFullscreen();}
}fullscreen(document.documentElement);