Javascript - 图片加载

Question

我的 js 文件中有一个函数来获取文件高度。

Util.isImageSize = function (file, callback) {
    var fileUpload = file;
    var reader = new FileReader();
    reader.readAsDataURL(fileUpload.files[0]);
    reader.onload = function (e) {
        var image = new Image();
        image.src = e.target.result;
        image.onload = function () {
            var height = this.height;
            callback(height);
        };
    }
}

这是我调用函数的地方

Util.isImageSize(document.getElementById('fileImage'), function(height) { 
    alert(height);
});

我收到错误提示

Uncaught TypeError: callback is not a function at Image.image.onload 

我现在真的很纠结

Answer 1

我不确定你在找什么，但我仍然可以提醒图像高度

var Util = {};

Util.isImageSize = function (file, callback) {
    console.log(file);
    var fileUpload = file;
    var reader = new FileReader();
    reader.readAsDataURL(fileUpload.files[0]);
    reader.onload = function (e) {
        var image = new Image();
        image.src = e.target.result;
        image.onload = function () {
            var height = this.height;
            callback(height);
        };
    }
}


document.getElementById('fileImage').addEventListener('change', function() {
    Util.isImageSize(this, function(height) { 
    alert(height);
});
})

http://jsfiddle.net/LvsYc/15487/