I've always appreciated these tools: Expresso and XPath Builder. They make designing regular expressions and XPath selectors almost fun! Did I say fun? I meant less painful. Being able to paste/load text and then interactively play with
the search criteria is infinitely better than
the code/compile/run/test cycle. It's faster and you get a much better feel for how
the expressions work.
So, I decided to make my own interactive tool to test jQuery selectors: jQuery Selector Tester.
Here's a sneak peek:
Note: There are some existing tools you may like better:
http://www.woods.iki.fi/interactive-jquery-tester.html
http://www.w3schools.com/jquery/trysel.asp?filename=trysel_basic&jqsel=p.intro,%23choose
My tool is different:
It is one page. You can save it and run it locally without a Web Server.
It shows
the results as a list of iterated objects instead of highlighted html.
A cheat sheet is on
the same page as
the tester which is handy.
I couldn't upload an .htm or .html file to this site so I hosted it on my personal site here: jQuery Selector Tester.
Design Highlights:
To make
the interactive search work, I added a hidden div to
the page:
<!--Hidden div holds DOM elements for jQuery to search--><div id="HiddenDiv" style="display: none"></div>
When ready to search,
the searchable html text is copied into
the hidden div…this renders
the DOM tree
in the hidden div:
// get
the html to search, insert it to
the hidden divvar Html = $("#TextAreaHTML").val();$("#HiddenDiv").html(Html);
When doing a search, I modify
the search pattern to look only
in the HiddenDiv. To do that, I put a space between
the patterns.
The space is
the Ancestor operator (see
the Cheat Sheet):
// modify search string to only search
in our// hidden div and do
the searchvar SearchString = "#HiddenDiv " + SearchPattern;try{ var $FoundItems = $(SearchString);}
Big Fat Stinking Faux Pas:
I was about to publish this article when I made a big mistake: I tested
the tool with Mozilla FireFox. It blowed up…it blowed up real good.
In the past I’ve only had to target IE so this was quite a revelation.
When I started to learn JavaScript, I was disgusted to see all
the browser dependent code. Who wants to spend their time testing against different browsers and versions of browsers? Adding a bunch of ‘if-else’ code is a tedious and thankless task. I avoided client code as much as I could.
Then jQuery came along and all was good. It was browser independent and freed us from
the tedium of worrying about version N of
the Acme browser.
Right? Wrong!
I had used outerHTML to display
the selected elements.
The problem is Mozilla FireFox doesn’t implement outerHTML.
I replaced this:
// encode
the html markupvar OuterHtml = $('<div/>').text(this.outerHTML).html();
With this:
// encode
the html markupvar Html = $('<div>').append(this).html();var OuterHtml = $('<div/>').text(Html).html();
Another problem was that Mozilla FireFox doesn’t implement srcElement.
I replaced this:
var Row = e.srcElement.parentNode;
With this:
var Row = e.target.parentNode;
Another problem was
the indexing.
The browsers have different ways of indexing.
I replaced this:
// this cell has
the search pattern var Cell = Row.childNodes[1]; // put
the pattern
in the search
box and search $("#TextSearchPattern").val(Cell.innerText);
With this:
// get
the correct cell and
the text
in the cell// place
the text
in the seach
box and serachvar Cell = $(Row).find("TD:nth-child(2)");var CellText = Cell.text();$("#TextSearchPattern").val(CellText);
So much for
the myth of browser independence. Was I overly optimistic and gullible? I don’t think so. And when I get my millions from
the deposed Nigerian prince I sent money to, you’ll see that having faith is not futile.
Notes:
My goal was to have a single standalone file. I tried to keep
the features and CSS to a minimum–adding only enough to make it useful and visually pleasing.
When testing, I often thought there was a problem with
the jQuery selector. Invariable it was invalid html code. If your results aren't what you expect, don't assume it's
the jQuery selector pattern:
The html may be invalid.
To help
in development and testing, I added a double-click handler to
the rows
in the Cheat Sheet table. If you double-click a row,
the search pattern is put
in the search
box, a search is performed and
the page is scrolled so you can see
the results. I left
the test html and code
in the page.
If you are using a CDN (non-local) version of
the jQuery libraray,
the designer
in Visual Studio becomes extremely slow. That's why there are two version of
the library
in the header and one is commented out.
For reference, here is
the jQuery documentation on selectors:
http://api.jquery.com/category/selectors/
Here is a much more comprehensive list of CSS selectors (which jQuery uses):
http://www.w3.org/TR/CSS2/selector.html
I hope someone finds this useful.
Steve WellensCodeProject
