js读取选取的文件内容

<input type="file" id="files" name="files[]" multiple />
<output id="list"></output>
<script>
var file_content = [];
function handleFileSelect(evt) {
    var file = evt.target.files[0]; // FileList object
    var reader = new FileReader();
    reader.onload = (function(theFile) {
        return function(e) {
            file_content.push(e.target.result);
        };
    })(file);

    reader.onloadend = function() {
        console.log(123);
        var str = file_content[0];
        $file_list = str.split(/\s+/);
        console.log($file_list);
    };
    reader.readAsText(file);
}
document.getElementById('files').addEventListener('change', handleFileSelect, false);
</script>