HTML5 File API: How to see the result of readAsText()

问题

When readAsText() function is completed the result is stored in .result

How do I see if the content of the file read are correct in .result?

 fr = new FileReader();
 fr.readAsText(file);
 var x = fr.result;
 console.log(x); //does not display anything on console

Now how do I display the .result object to verify the the content?

回答1:

readAsText is asynchronous, so you would need to use the onload callback to see the result.

Try something like this,

var fr = new FileReader();
fr.onload = function(e) {
    // e.target.result should contain the text
};
fr.readAsText(file);

Further information here,

https://developer.mozilla.org/en-US/docs/DOM/FileReader

来源：https://stackoverflow.com/questions/13729301/html5-file-api-how-to-see-the-result-of-readastext