forked from uglyjs/uglyjs.github.com
Commit
This commit does not belong to any branch on this repository, and may belong to a fork outside of the repository.
Merge pull request uglyjs#5 from mathiasbynens/master
New blog post + some random tweaks from mathias bynens
- Loading branch information
Showing
4 changed files
with
90 additions
and
48 deletions.
There are no files selected for viewing
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,32 @@ | ||
| --- | ||
| title: Useless use of <code>document.write</code> | ||
| layout: post | ||
| author: Mathias Bynens | ||
| authorurl: http://mathiasbynens.be/ | ||
| --- | ||
|
|
||
| While reviewing some [enterprise JavaScript](http://enterprise-js.com/) for a client I came across a couple of these inside `if` clauses: | ||
|
|
||
| {% highlight javascript %} | ||
| document.write("<scr"+"ipt language=javascript>var some_var = 'some value'<" + "/scr"+"ipt>"); | ||
| {% endhighlight %} | ||
|
|
||
| There’s definitely some room for improvement here. For one, the `language` attribute on the `<script>` element is obsolete in HTML; it can safely be omitted. | ||
|
|
||
| {% highlight javascript %} | ||
| document.write("<scr"+"ipt>var some_var = 'some value'<" + "/scr"+"ipt>"); | ||
| {% endhighlight %} | ||
|
|
||
| Next, there’s no need to concatenate the string like that — you can just write it out all at once, as long as you [escape the `</script>` end tag](http://mathiasbynens.be/notes/etago "Technically, this isn’t needed if you’re certain the JavaScript will never be used inline in the HTML."): | ||
|
|
||
| {% highlight javascript %} | ||
| document.write("<script>var some_var = 'some value'<\/script>"); | ||
| {% endhighlight %} | ||
|
|
||
| There are only few good reasons to ever use `document.write`. Writing out `<script>` elements _can_ be one of them, but in this case? Not so much. Believe it or not, the intention of this code snippet was to **create a global variable**. (Polluting the global scope with variables is something that should be avoided whenever possible; however, in this case, the variable really needed to be global.) | ||
|
|
||
| Of course, there’s a better way to do that in client-side JavaScript: | ||
|
|
||
| {% highlight javascript %} | ||
| window.some_var = 'some value'; | ||
| {% endhighlight %} |
Sorry, something went wrong. Reload?
Sorry, we cannot display this file.
Sorry, this file is invalid so it cannot be displayed.
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters