why "Single-quoted string preferred over double-quoted string." in js?

Whi开发者_JAVA技巧le using gjslint, I got a hint: "Single-quoted string preferred over double-quoted string".

So why? I'm a little confused with this. Why single-quoted preferred?

Hope to get some help. Thanks all.

It's just somebody's opinion.

Lots of people do prefer singe-quotes, but lots of other people prefer double-quotes. I tend to use double-quotes just out of habit from other languages, but I don't have a strong preference: I'm willing to change if I hear of a compelling reason why single-quotes are better, but to date I've not even heard a good reason, let alone a compelling reason.

Even the Google JavaScript Style Guide says that single-quotes are preferred without giving a good reason:

"For consistency single-quotes (') are preferred to double-quotes ("). This is helpful when creating strings that include HTML"

(It then goes on to give a very short example of a string that doesn't even include HTML.)

A lot of people seem to believe XHTML is only valid with double-quotes, but that is not true: the XHTML spec allows either. (Having said that, 98% of the XML I've run across, including XHTML, does use double-quotes.)

Within any one source file I try to stick to one or the other, but if a line of code in the middle needed a lot of embedded quotes I'd be happy to change for just that line to avoid lots of escaping in that line.

UPDATE: Just remembered that JSON is only valid with double-quotes. Obviously JSON is not JavaScript, but still that's a reason why (a) some might prefer double-quotes in their JavaScript so that object literals look like JSON, and (b) some might prefer single-quotes so that they can manually encode JSON without having to escape the double-quotes. (No, I don't recommend manually encoding JSON, but I've seen it done.)

If you use single quotes, you do not have to escape the double quotes in your html.

For example...

With single quotes you can do this

var a = '<a href="something.html" rel="yes" title="whatever">a link/a>';

with double quotes you would need to escape those inside double quotes, like so

var a = "<a href=\"something.html\" rel=\"yes\" title=\"whatever\">a link/a>";

Much more work, more difficult to maintain, and easier to commit errors.

My keyboard has a '/" key so I can easily type a single quote but need to press shift for the double quote. :)

As for the JSLint warnings its just trying to enforce an arbitrary standard in order to promote a more consistent coding style, just like how it does on other spacing and indentation issues.

In terms of performance, according with http://jsperf.com you get almost the same performance for both in some browsers, in others you get the same performance.

There's a lot of tests in jsperf and all of them get almost the same result:

• http://jsperf.com/double-or-simple-quote
• http://jsperf.com/quotes-compare
• http://jsperf.com/jquery-double-vs-single-quotes
• http://jsperf.com/search?q=quote

In conclusion I think using single or double quotes is just a matter of taste and not a matter of performance.

Regards.