判断数据类型

function isType(param){
    //1.判断是不是字符串对象
    if(typeof param === 'string' && param.constructor == String){
        return "String";
    }

    //2.判断是不是数字对象
    if(typeof param === 'number' && param.constructor == Number){
        return "Number";
    }

    //3.判断是否为数组类型
    if(typeof param === 'object' && param.constructor == Array){
        return "Array";
    }

    //4.判断是否是日期类型
    if(typeof param === 'object' && param.constructor == Date){
        return "Date";
    }

    //5.判断是否为函数
    if(typeof param === 'function' && param.constructor == Function){
        return "Function";
    }

    //6.判断是否为普通的对象
    if(typeof param === 'object' && param.constructor == Object){
        return "Object";
    }
}

百度自动选择效果

$("#libfiles").off("mouseenter", "li");
$("#libfiles").on("mouseenter", "li", function(e){
    var text = $(this),
        range,
        selection;

    if(!text.length) return;
    text = text[0];

    if (document.body.createTextRange) {
        range = document.body.createTextRange();
        range.moveToElementText(text);
        range.select();
    } else if (window.getSelection) {
        selection = window.getSelection();
        range = document.createRange();
        range.selectNodeContents(text);
        selection.removeAllRanges();
        selection.addRange(range);
    }
});

清除文本选中状态

if(document.selection && document.selection.empty){
    document.selection.empty(); //IE
}else if(window.getSelection){
    window.getSelection().removeAllRanges();    //FF
}

IE当鼠标移除窗口之后仍能捕获事件

if(curObj.setCapture){
    curObj.setCapture(true);
}

IE释放捕获

if(curObj.releaseCapture){
    curObj.releaseCapture(true);
}

浏览器检测

//Opera
window.opera+"" == [window opera]

//IE
window.ActiveXObject
navigator.userAgent.indexOf("msie");

//Firefox
typeof document.mozHidden != 'undefined'

加载IE6-IE8中的脚本文件

if (!document.addEventListener) {
  // IE6~IE8
  document.write('<script src="ieBetter.js"><\/script>');
}

元素在页面上的偏移量

var rect = el.getBoundingClientRect()
return {
  top: rect.top + document.body.scrollTop,
  left: rect.left + document.body.scrollLeft
}

视口大小

// ie9+
var pageWidth = window.innerWidth,
    pageHeight = window.innerHeight;
if (typeof pageWidth != "number"){
  // ie8
  if (document.compatMode == "CSS1Compat"){
    pageWidth = document.documentElement.clientWidth;
    pageHeight = document.documentElement.clientHeight;
  } else {
    // ie6混杂模式
    pageWidth = document.body.clientWidth;
    pageHeight = document.body.clientHeight;
  }
}

判断是不是IE浏览器

function isIE(){
    if(!!window.ActiveXObject || "ActiveXObject" in window){
        return true;
    }else{
        return false;
    }
};

判断是PC端还是mobile端

function IsPC() {
    var userAgentInfo = navigator.userAgent;
    var Agents = new Array("Android", "iPhone", "SymbianOS", "Windows Phone", "iPad", "iPod");
    var flag = true;
    for (var v = 0; v < Agents.length; v++) {
        if (userAgentInfo.indexOf(Agents[v]) > 0) {
            flag = false;
            break
        }
    }
    return flag
}

手机页面缩放工具

var phoneWidth =  parseInt(window.screen.width);
var phoneScale = phoneWidth/origionWidth;
var ua = navigator.userAgent;

if(/Android (\d+\.\d+)/.test(ua)){
    document.write('<meta name="viewport" content="width=' + origionWidth + ', minimum-scale = '+phoneScale+', maximum-scale = '+phoneScale+', target-densitydpi=device-dpi">');
}else{
    document.write('<meta name="viewport" content="width=' + origionWidth + ', user-scalable=no">');
}

判断手机横竖屏状态

window.addEventListener("onorientationchange" in window ? "orientationchange" : "resize", function() {
    if (window.orientation === 180 || window.orientation === 0) { 
        alert('竖屏状态！');
    } 
    if (window.orientation === 90 || window.orientation === -90 ){ 
        alert('横屏状态！');
    }  
}, false); 

手机自动缩放图片

$(function() {

    function resizeBaseFontSize() {
        var rootHtml = document.documentElement,
            deviceWidth = rootHtml.clientWidth;
        if(deviceWidth > 640) {
            deviceWidth = 640;
        }

        rootHtml.style.fontSize = deviceWidth / 7.5 + "px";
    }

    resizeBaseFontSize();

    window.addEventListener("resize", resizeBaseFontSize, false);
    window.addEventListener("orientationchange", resizeBaseFontSize, false);
})