jQuery检查前置是否失败 [英] JQuery check if prepend failed

问题描述

关于如何测试prepend()是否成功的任何想法? Prepend()当然不适用于图像标签，因此我需要执行before().

Any ideas on how I would test if prepend() succeeds? Prepend() doesn't work on an image tag of course so I need to perform before().

我正在尝试使用.query类在所有跨度之前添加图像，但无法使其在包含自封闭标签(如图像)的跨度上工作.

I'm trying to prepend an image to all spans with a class of .query, but cannot get it to work on spans that contain self closing tags like images.

尝试过:

$('.query').each(function(i) {
  var elm=$(this);
  if (elm.prepend('<img class="fold" src="/img/fold.png" />').find('img.fold').length==0) {
    elm.before('<img class="fold" src="/img/fold.png" />');
  }
});

开启:

<span class="query">
  <img alt="blah" src="img/banner.jpg" height="422" width="952" />
</span>
<span class="query">
  <p>Lorem ipsum dolor sit amet, consectetur adipiscing elit. Vestibulum ornare, tellus in posuere viverra, dui dolor lacinia elit, vitae vestibulum nuluris condimentum. Donec vel mauris t sed sit amet. Class aptent taciti sociosqu ad litora torquent per conubia nostra, per inceptos himenaeos</p>
</span>

没有答案，所以我现在可以解决:

No answers so I have a work around for now:

if (elm[0].tagName.toLowerCase()=="img") {
    elm.before('<img class="fold" src="/img/fold.png" />');
}
else {
    elm.prepend('<img class="fold" src="/img/fold.png" />')
}

推荐答案

因为我无法检测到prepend是否失败，所以我检测到prepend是否会失败.

Since I you cannot detect if prepend fails I detected if prepend will fail with.

if (elm.is(':empty')) {
    elm.before('<img class="fold" src="/img/fold.png" />');
}
else {
    elm.prepend('<img class="fold" src="/img/fold.png" />');
}

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