Welcome to OGeek Q&A Community for programmer and developer-Open, Learning and Share
Welcome To Ask or Share your Answers For Others

Categories

0 votes
697 views
in Technique[技术] by (71.8m points)

javascript - Double dollar $$() vs Dollar sign $() in Chrome console behavior

In our project, there is a different functionality when one Dollar sign used $() in Chrome console vs two Dollar signs $$(), besides the known difference that $$() return an array an $() return the first element.

For example, selector for specific element, with one dollar and two dollar queries:

$$(".my-class[my-attribute='trump']") //works

$('.my-class[my-attribute=sanders]') //works

$$('.my-class[my-attribute=trump]') //not work

What is the source and explanation for this behavior?

See Question&Answers more detail:os

与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…
Welcome To Ask or Share your Answers For Others

1 Reply

0 votes
by (71.8m points)

From Chrome Developer Tools documentation:

Selecting Elements

There are a few shortcuts for selecting elements. These save you valuable time when compared to typing out their standard counterparts.

$() Returns the first element that matches the specified CSS selector. It is a shortcut for document.querySelector().

$$() Returns an array of all the elements that match the specified CSS selector. This is an alias for document.querySelectorAll()

$x() Returns an array of elements that match the specified XPath.

When you use querySelector (or $), the result is an element or null. When you use $$, the result isn't an element but an Array which can be easily iterated over. This differs from the native querySelectorAll where it returns a NodeList which is slightly harder to go over all the entries.

Regarding the quote: of course it works the same. See:

enter image description here

Conclusion: It's useless to quote trump. You might also end insane.


与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…
OGeek|极客中国-欢迎来到极客的世界,一个免费开放的程序员编程交流平台!开放,进步,分享!让技术改变生活,让极客改变未来! Welcome to OGeek Q&A Community for programmer and developer-Open, Learning and Share
Click Here to Ask a Question

...