javascript - turn image into string from

Question

Is it possible to turn an image into a base64 string with these restrictions,

1. Image is coming from <input type="file"/>
2. No internet connection
3. Mobile Browser

I know I can download an image and convert it using <canvas>, but is it possible to access the image before it's uploaded? If this is not possible I am going to write a PhoneGap plugin.

Thanks!

Edit-

Got this working using the FileReader API. Here's the relivant code,

var reader = new FileReader();
reader.onload = function(theFile) {
    var base64Image = theFile.srcElement.result;
};

// Read in the image file as a data URL.
reader.readAsDataURL(image.fileElement.dom.files[0]);

Answer 1

拦截submit表单上的事件，并读取那里的数据。如果需要，您可以中止提交，并将数据保存在本地。