javascript 怎样把闭包里处理得到值传到闭包外面，使闭包外面的变量af的值和闭包里af的值同步变化、相等？

ToSurpassTesla 2012-08-10 11:46:15

<!DOCTYPE HTML>

<html>

<head>

  <title>Canvas </title>

  <style type="text/css">

    .thumb {

    height: 75px;

    border: 5px solid #000;

    margin: 20px 10px 0 0;

  } 

  </style>

 

</head>

<body>

 <input type="file" id="files" name="files[]" multiple />

<output id="list"></output>

<script>

    var af = 2;//闭包外的af

    document.getElementById('files').addEventListener('change', handleFileSelect, false);

    function handleFileSelect(evt) {

        var files = evt.target.files; // FileList object

        for (var i = 0, f; f = files[i]; i++) {

            // Only process image files.

            if (!f.type.match('image.*')) {

                continue;

            }

            var reader = new FileReader();

            reader.onload = function test(e) {

                var df = 60;

                var dataUri = event.target.result;

                af = 10 + df + i; //闭包里的af

                img = new Image();

                img.src = dataUri;

                document.body.appendChild(img);

                alert(af);// 弹出闭包里af的值

            }

            reader.readAsDataURL(f);

        }

        alert(af); //弹出闭包外的af的值

    }

</script>

</body>

</html>

怎样把闭包里处理得到值传到闭包外面，使闭包外面的变量af的值和闭包里af的值同步变化、相等？？

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ToSurpassTesla 2012-08-13

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[Quote=引用 2 楼的回复:]

function handleFileSelect(evt) {
var files = evt.target.files; // FileList object
var testAf = this;
for (var i = 0, f; f = files[i]; i++) {
// Only process ……
[/Quote]
虽然不行，不过还是很谢谢你的帮助!!!!

ToSurpassTesla 2012-08-13

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[Quote=引用 3 楼的回复:]

<!DOCTYPE HTML>
<html>
<head>
<title>Canvas </title>
<style type="text/css">
.thumb {
height: 75px;
border: 5px solid #000;
margin: 20px 10px 0 0;
}
</style>

</……
[/Quote]
很有道理，遇到困难，最聪明的方法就是绕过困难....谢谢

zhaozhenall 2012-08-13

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IR_Chairman 2012-08-13

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<!DOCTYPE HTML>
<html>
<head>
<title>Canvas </title>
<style type="text/css">
.thumb {
height: 75px;
border: 5px solid #000;
margin: 20px 10px 0 0;
}
</style>

</head>
<body>
<input type="file" id="files" name="files[]" multiple />
<output id="list"></output>
<script>
var af = 2;//闭包外的af
document.getElementById('files').addEventListener('change', handleFileSelect, false);
function handleFileSelect(evt) {
var files = evt.target.files; // FileList object
for (var i = 0, f; f = files[i]; i++) {
// Only process image files.
if (!f.type.match('image.*')) {
continue;
}
// var reader = new FileReader();
var canvas = document.createElement("canvas");
var dataUri = canvas.toDataURL("image/png");
}
alert(af); //弹出闭包外的af的值
}
</script>
</body>
</html>
其实你可以用其它方法来把onload事件取代吧！这样会变得简单多了....

xd4005 2012-08-12