一、图片转base64并压缩

//input file选中文件后调用
change(self){
    self = self.target
    //创建一个读取文件的对象
    let reader = new FileReader();
    //读取文件，转码
    reader.readAsDataURL(self.files[0]);
    reader.onload = function (e) {
        let base64 = e.target.result; //转码过后的base64编码
        //创建一个图片
        let newImage = new Image();
        let quality = 0.6;    //压缩系数0-1之间，压缩到0.9以上会有bug，注意！（可以自行设置）
        newImage.src = base64;
        newImage.setAttribute("crossOrigin", 'Anonymous');  //url为外域时需要
        let imgWidth, imgHeight;
        newImage.onload = function () {
            imgWidth = this.width;
            imgHeight = this.height;
            //给生成图片设置一个默认的最大宽/高（可以自行设置）
            let myWidth = 800;
            //准备在画布上绘制图片
            let canvas = document.createElement("canvas");
            let ctx = canvas.getContext("2d");
            //判断上传的图片的宽高是否超过设置的默认最大值，以及设置同比例的宽高
            if (Math.max(imgWidth, imgHeight) > myWidth) {
                if (imgWidth > imgHeight) {
                    canvas.width = myWidth;
                    canvas.height = myWidth * imgHeight / imgWidth;
                } else {
                    canvas.height = myWidth;
                    canvas.width = myWidth * imgWidth / imgHeight;
                }
            } else {
                canvas.width = imgWidth;
                canvas.height = imgHeight;
            }
            //清空画布
            ctx.clearRect(0, 0, canvas.width, canvas.height);
            //开始绘制图片到画布上
                ctx.drawImage(this, 0, 0, canvas.width, canvas.height);
                let newBase64 = canvas.toDataURL("image/jpeg", quality);//压缩图片大小（关键代码）
            // 获取到当前的图片的大小，然后调整成自己需要的大小，例如说需要200KB-500KB之间（可以自行设置）
            while (newBase64.length / 1024 > 200) {
                quality -= 0.2;
                newBase64 = canvas.toDataURL("image/jpeg", quality);
            }
            //压缩完成
            upload(newBase64)
        }
    };
}

二、IE浏览器判断

function IEVersion() {
    var userAgent = navigator.userAgent; //取得浏览器的userAgent字符串  
    var isIE = userAgent.indexOf("compatible") > -1 && userAgent.indexOf("MSIE") > -1; //判断是否IE<11浏览器  
    var isEdge = userAgent.indexOf("Edge") > -1 && !isIE; //判断是否IE的Edge浏览器  
    var isIE11 = userAgent.indexOf('Trident') > -1 && userAgent.indexOf("rv:11.0") > -1;
    if(isIE) {
        var reIE = new RegExp("MSIE (\\d+\\.\\d+);");
        reIE.test(userAgent);
        var fIEVersion = parseFloat(RegExp["$1"]);
        if(fIEVersion == 7) {
            return 7;
        } else if(fIEVersion == 8) {
            return 8;
        } else if(fIEVersion == 9) {
            return 9;
        } else if(fIEVersion == 10) {
            return 10;
        } else {
            return 6;//IE版本<=7
        }   
    } else if(isEdge) {
        that.isIE11 = true;
        return 'edge';//edge
    } else if(isIE11) {
        that.isIE11 = true;
        return 11; //IE11  
    }else{
        return -1;//不是ie浏览器
    }
}

三、判断ios和安卓

var u = navigator.userAgent;
var isAndroid = u.indexOf('Android') > -1 || u.indexOf('Adr') > -1; //android终端
var isiOS = !!u.match(/\(i[^;]+;( U;)? CPU.+Mac OS X/); //ios终端

四、获取url链接上的参数

function getQueryString(name) {
    var reg = new RegExp("(^|&)" + name + "=([^&]*)(&|$)", "i");
    var r = window.location.search.substr(1).match(reg);
    if(r != null) return r[2];
    return "";
};

五、阻止事件冒泡和禁用鼠标事件

//阻止冒泡
e.stopPropagation();
//css禁用鼠标事件
pointer-events: none;

六、JSEncrypt RSA加密、解密

//加密
//公钥
var _key = 'MIGfMA0GCSqGSIb3DQEBAQUAA4GNA0h2gpFTwIDAQAB';
var encryptObj = new JSEncrypt();
encryptObj.setPublicKey(_key);
return encryptObj.encrypt(str);
//解密
//私钥
var privateKey = 'MIICdgIBADANBgkqhkiG9w0BAQEFAASUxeg=='
var decrypt = new JSEncrypt();
decrypt.setPrivateKey(privateKey);
return decrypt.decrypt(value);

七、获取浏览器类型

function getBrowserType(callback) {
    var ua = navigator.userAgent;
    if (navigator.appName == "Microsoft Internet Explorer" || ua.indexOf("Trident") > -1) {
      return "IE";
    } else if (ua.indexOf("Chrome") > -1) {
        return "Chrome";
    } else if (ua.indexOf("Safari") > -1) {
        return "Safari";
    } else if (ua.indexOf("Firefox") > -1) {
        return "Firefox";
    } else {
        return "unknown";
    }
}