js 压缩图片

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var f = data[0];  //图片地址 var xhr = new XMLHttpRequest() xhr.open('GET', f, true) xhr.responseType = 'blob' xhr.onload = function() {     console.log("到此了");     console.log(this.response.size);     if(this.response.size>250000){         let img = new Image();          img.src = f; // 要压缩的图片         let width=0;         let height=0;         img.onload=function(){              width = img.width;              height = img.height;                         let canvas = document.createElement('canvas');             let ctx = canvas.getContext('2d');             canvas.width = width;             canvas.height = height;             var base64;             //  将图片画到canvas上面   使用Canvas压缩               canvas.setAttribute("width", width);                                               canvas.setAttribute("height",height);             ctx.drawImage(this, 0, 0, width, height);             //var base64 = canvas.toDataURL(this.response.type, 0.2);             var base64 = canvas.toDataURL('image/png',0.2);             console.log(base64);//最终获得base64位             console.log("到此了");        };     }else{<br>                                                               //此方法自行写 pathToBase64             pathToBase64(f).then(res=>{                 console.log(res);直接转base64             })     }

　　

参考地址:

https://www.cnblogs.com/zhao1949/p/9177281.html

https://www.jq22.com/web-skill43

https://www.jb51.net/article/187561.htm

https://www.jianshu.com/p/d21193898339

https://developer.mozilla.org/zh-CN/docs/Web/API/HTMLImageElement/Image

https://www.cnblogs.com/markor/articles/745281.html   [图片类处理]