javascript检查json是否为null [英] javascript check if null from json

问题描述

我正在使用以下JavaScript.它写得很好，直到得到没有值的结果为止.在控制台日志中，它显示了

Im using the following javascript. it writes fine until it gets to a result which doesn't have a value. in console log it shows this

未捕获的TypeError:无法读取null的属性文本"

Uncaught TypeError: Cannot read property 'text' of null

但是我下面的脚本似乎不起作用

but my script below doesn't seem to work

            var checkCaption = photo.caption.text;
            if (checkCaption == null) {
                caption = 'meh';
            } else {
                caption = photo.caption.text;
            }

推荐答案

在您的示例中，photo.caption为空，因此您的代码在完成检查之前在photo.caption.text调用上中断.

In your example, photo.caption is null, so your code breaks on the photo.caption.text call, before the check is done.

var caption;

if(photo.caption != null) { // Covers 'undefined' as well
  caption = photo.caption.text;
} else {
  caption = "meh";
}

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