为什么jQuery中的代码不起作用？

Question

the url is as this: http://example.com/download/

var pathname = window.location.pathname;
if(pathname=='download/'){
$("#subnav-content div:first").hide();
$("#subnav-content div:second").show();
}

why the above code in jquery doesn't work? i want to when the url is http://example.com/download/ . show the secong div.

ps* :does this check affect the site performance? *

Answer 1

You need the leading slash.

'/download/'

If you expect query string parameters you may try a regular expression to just match the download portion of the url: the following matches /download/.

if (window.location.pathname.match(/^\/download\//i))

Regarding the jquery, there is no :second, you need to use :eq(1)

var pathname = window.location.pathname;
if(pathname=='/download/'){
$("#subnav-content div:first").hide();
$("#subnav-content div:eq(1)").show();
}

Response to comments

I'm putting my comment here because the formatting is horrible in the comments. The regular expression for matching download can be summed up as follows:

/ - start of regular expression matching syntax
^ - means start matching at the very start of the screen
\\/ - means match the literal string '/', which is a special character which must be escaped
download - match the literal string 'download'
\\/ - again means match the literal string '/'
/ - end of the matching syntax
i - regular expression options, i means ignore case

It was not clear to me what your other note was asking for.

Answer 2

Second is not a selector. You want:

$("#subnav-content div:nth-child(2)").show();

Answer 3

Try using

$("#subnav-content div:eq(0)")
$("#subnav-content div:eq(1)")

Also, you need to bind the code to an Event that will get fired when the Document is ready( load , or onDOMReady where supported) otherwise the div s might not exist in memory yet.

ps*:does this check affect the site performance?*

Every line of code has an effect on site performance. Not necessarily a visible one although.