Angular js - isImage() - 通过 url 检查它是否是图像 [英] Angular js - isImage( ) - check if it's image by url

问题描述

是否可以通过给定的 url 检查图像是否存在并且它是图像资源?

例如:

angular.isImage('http://asd.com/asd/asd.jpg')

或者它只是服务器端的东西?

NO JQUERY 请我不要使用它

解决方案

我认为最好的 javascript 方法是使用带有延迟对象的 HTMLImageElement 对象:

function isImage(src) {var deferred = $q.defer();var image = new Image();image.onerror = function() {deferred.resolve(false);};image.onload = function() {deferred.resolve(true);};image.src = src;返回 deferred.promise;}

用法:

isImage('http://asd.com/asd/asd.jpg').then(function(test) {控制台日志(测试)；});

使用 HTMLImageElement 给你带来一些好处:不仅可以测试文件是否可下载，而且它是可以通过 img 标签显示的有效图像资源.>

我将此代码包装在简单的服务中以进行测试，它似乎有效:

app.controller('MainCtrl', function($scope, Utils) {$scope.test = function() {Utils.isImage($scope.source).then(function(result) {$scope.result = 结果；});};});app.factory('Utils', function($q) {返回 {isImage: 函数(src) {//... 以上 isImage 函数的代码}};});

演示:http://plnkr.co/edit/u5F6FfO3dEkNSMYV1amo?p=preview

Is it possible to check if by a given url the image exists and it's an image resource ?

for example:

angular.isImage('http://asd.com/asd/asd.jpg')

Or it's just a stuff for the server side ?

NO JQUERY please i'm not using it

解决方案

I think the best javascript approach would be to use HTMLImageElement object with deferred object:

function isImage(src) {

    var deferred = $q.defer();

    var image = new Image();
    image.onerror = function() {
        deferred.resolve(false);
    };
    image.onload = function() {
        deferred.resolve(true);
    };
    image.src = src;

    return deferred.promise;
}

Usage:

isImage('http://asd.com/asd/asd.jpg').then(function(test) {
    console.log(test);
});

Using HTMLImageElement gives you some benefits: not only it tests that the file is downloadable but also it is valid image resource that can be displayed by img tag.

I wrapped this code in simple service to make a test and it seems to work:

app.controller('MainCtrl', function($scope, Utils) {
    $scope.test = function() {
        Utils.isImage($scope.source).then(function(result) {
            $scope.result = result;
        });
    };
});

app.factory('Utils', function($q) {
    return {
        isImage: function(src) {
            // ... above code for isImage function
        }
    };
});

Demo: http://plnkr.co/edit/u5F6FfO3dEkNSMYV1amo?p=preview

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