码蚁原创，请大神多多指教（嘻嘻，有同事帮忙改进的）
<script>
/**
*
* @param id {string} input[file] elementID
* @param width {number} 宽度
* @param quality{number} 压缩质量 {0.1-1}
* @param callback{function} 回调函数 默认参数{code: number, data: string}
*/
function min_img(id,callback,width,quality){
var a={
width:width || 640,
quality:quality || 0.8
}
a.readFile= function(){
var file = this.files[0];
if (!/image\/\w+/.test(file.type)) {
callback({code:101,data:'格式错误'});
}else{
var reader = new FileReader();
reader.readAsDataURL(file);
reader.onload = function(e) {
var img = new Image(),
// quality = 0.8, //image quality
canvas = document.createElement('canvas'),
drawer = canvas.getContext("2d");
img.src=e.target.result;
img.onload=function(){
a.height = a.width * (img.height / img.width);
canvas.width=a.width;
canvas.height=a.height;
drawer.drawImage(img, 0, 0, a.width, a.height);
a.result = canvas.toDataURL("image/jpeg",a.quality);
callback({code:100,data:a.result})
}
}
}
}
if (typeof(FileReader) === 'undefined') {
callback({code:102,data:'浏览器不支持'});
} else {
var input = document.getElementById(id);
input.addEventListener('change', a.readFile, false);
}
}
</script>啦啦啦~~~自己用着挺好的，希望能帮助到你哦
