js 将远程图片转化为base64及下载远程图片

//将远程图片转化为base64
getBase64(img){
function getBase64Image(img,width,height) {//width、height调用时传入具体像素值，控制大小 ,不传则默认图像大小
var canvas = document.createElement("canvas");
canvas.width = width ? width : img.width;
canvas.height = height ? height : img.height;

var ctx = canvas.getContext("2d");
ctx.drawImage(img, 0, 0, canvas.width, canvas.height);
var dataURL = canvas.toDataURL();
return dataURL;
}
var image = new Image();
image.crossOrigin = '';
image.src = img;
return new Promise((resolve,reject)=>{
image.onload =function (){
resolve(getBase64Image(image));//将base64传给done上传处理
}
});
}

getBase64('http://xxx.com/xx.jpg').then(base64 => {
console.log(base64)
}, err => {
console.log(err)
})

//下载远程图片
downloadFile(url) {
var aLink = document.createElement('a');
var evt = document.createEvent("MouseEvents");
evt.initEvent("click", false, false);
aLink.download = url;
aLink.href = url;
aLink.dispatchEvent(evt);
}

downloadFile('http://xxx.com/xx.jpg')