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实用js方法DataUrl转为File、url转base64

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1,DataUrl转为File

 1 /**  2 * DataUrl转为File  3 * @param {String} dataUrl - dataUrl地址  4 * @param {String} fileName - file文件名  5 */  6 dataURLtoFile(dataUrl, fileName){  7     var arr = dataUrl.split(','), mime = arr[0].match(/:(.*?);/)[1],  8         bstr = atob(arr[1]), n = bstr.length, u8arr = new Uint8Array(n);  9     while(n--){ 10         u8arr[n] = bstr.charCodeAt(n); 11     } 12     return new File([u8arr], fileName, {type:mime}); 13 }

2,url转base64

/** * url转base64 * @param {String} url - url地址 */ urlToBase64(url) {     return new Promise ((resolve,reject) => {         let image = new Image();         image.onload = function() {             let canvas = document.createElement('canvas');             canvas.width = this.naturalWidth;             canvas.height = this.naturalHeight;             // 将图片插入画布并开始绘制             canvas.getContext('2d').drawImage(image, 0, 0);             // result             let result = canvas.toDataURL('image/png')             resolve(result);         };         // CORS 策略,会存在跨域问题https://stackoverflow.com/questions/20424279/canvas-todataurl-securityerror         image.setAttribute("crossOrigin",'Anonymous');         image.src = url;         // 图片加载失败的错误处理         image.onerror = () => {             reject(new Error('转换失败'));         };     }); } //使用例子 this.urlToBase64(this.Url).then(res=>{     console.log(res); })

3,生成Uuid

function CreateUuid() {     let Time = new Date().getTime();     let uuid = 'xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx'     .replace(/[xy]/g, function(res) {         let Random = (Time + Math.random() * 16) % 16 | 0;         Time = Math.floor(Time / 16);         return (res == 'x' ? Random : (Random & 0x3 | 0x8)).toString(16);     });     return "pdd"+ uuid; };

4,获取url路径后的参数

// 不传name返回所有值,否则返回对应值 function getUrlParams(name) {     var url = window.location.search;     if (url.indexOf('?') == 1) { return false; }     url = url.substr(1);     url = url.split('&');     var name = name || '';     var nameres;     // 获取全部参数及其值     for(var i=0;i<url.length;i++) {         var info = url[i].split('=');         var obj = {};         obj[info[0]] = decodeURI(info[1]);         url[i] = obj;     }     // 如果传入一个参数名称,就匹配其值     if (name) {         for(var i=0;i<url.length;i++) {             for (const key in url[i]) {                 if (key == name) {                     nameres = url[i][key];                 }             }         }     } else {         nameres = url;     }     // 返回结果     return nameres; }

5,Canvas生成水印

/** * Canvas生成水印 * @param {dom} element - dom元素 * @param {String} text - 水印文本 */ function watermark(element, text) {     var canvas = ''         , ctx = ''         , data = ''         , fontWidth = '12.5'         , node = document.querySelector(element)         , width = node.clientWidth         , height = node.clientHeight;     canvas = document.createElement("canvas");     canvas.width = "100";     canvas.height = "100";     ctx = canvas.getContext("2d");     ctx.clearRect(0, 0, 200, 200);     fontWidth = document.documentElement.clientWidth * 3 * 12.5 / 4000;     ctx.font = fontWidth + "px 黑体";     ctx.rotate(-20 * Math.PI / 180);     ctx.fillStyle = "rgba(0,0,0, .2)";     ctx.fillText(text, -20, 80);     data = canvas.toDataURL("image/png", 1);     node.style.background = 'url(' + data + ') repeat'; }; watermark("#canvas","相约1998");

6,请求本地Json

let Params = 'data/data.json'; var PddAjax2 = new Promise(PddAjax); // 成功 PddAjax2.then(function(res){     console.log(res) }) function PddAjax(resolve , reject){     this.Params = Params;     $.ajax({         type:'get',         url:Params,         success: function(res) {             resolve(res);         },         error: function(res) {             reject(res);         }     }) }

 

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