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jQuery Refactoring how we think about client-side scripting

jQuery Refactoring how we think about client-side scripting. Andrew Roazen Cline Library Technology Services February 8, 2011. What is jQuery ?. A library providing a superset of JavaScript An extensible, pluggable platform A way of more intuitively programming the Web.

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jQuery Refactoring how we think about client-side scripting

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  1. jQueryRefactoring how we think about client-side scripting Andrew Roazen Cline Library Technology Services February 8, 2011

  2. What is jQuery? • A library providing a superset of JavaScript • An extensible, pluggable platform • A way ofmore intuitively programming the Web

  3. Foundations of jQuery JavaScript (Brendan Eich, 1995) • Inspired by HyperCard’s interactivity and Java’s object-oriented features • Designed as “Java Lite” with a minimum of bloat and a shallow learning curve for Java/C programmers • Quickly cloned by MS: extended, embraced… but not extinguished

  4. Foundations of jQuery Problems with JavaScript • Incompatibility: No vendor consensus on implementation of object/event referencing, object positioning or even event capturing • CSS still a draft concept • Target audience largely not Java/C programmers • Massive reinvention of wheel to perform simple tasks

  5. Foundations of jQuery Cross-browser libraries (early 2000s) • Simple wrapper functions which replace incompatible native object referencing/event capturing functionality • The beginnings of effects libraries built on these wrapper functions (script.aculo.us, MooTools) • Libraries became larger and more complex but not proportionately mature • A tendency to focus on user experience rather than the broader underlying issue behind it: a low level language meant to solve a platform-specific task

  6. Foundations of jQuery CSS behaviors (IE-only, early 2000s) • Introduced the ability to attach function-based behaviors to classes rather than named objects • Benefits of prototyping without the overhead • Not part of any recognized standard • No adoption outside IE

  7. Enter jQuery jQuery(John Resig, 2006) • Inspired by: • IE’s CSS behaviors • CSS selector syntax • XLST (Xpath)selector syntax

  8. Enter jQuery jQuery(John Resig, 2006) • Selectors: object abstraction by Xpath-like queries describing/combining class, ID, tag, node relationship, attribute values, etc. • Code written as chainable methods applied to selector queries, making code compact and intent more concrete • Utility functions for the most common interactive content development tasks: • Xpath-flavored DOM node traversal / manipulation • Event handling, from simple capturing to complex delegation/queuing • Form control /control status selectors • Basic CSS effects/animation • AJAX / JSON / XML • .data() method for storing/querying arbitrary data structures in an element

  9. Enter jQuery jQuery(John Resig, 2006) • Unobtrusive JavaScript: script never appears inside <HTML>, separating content and controller • Nonbloated: Base library only 29K minified/gzipped, 207k uncompressed • Extensive plugins libraries as simple or complex as your needs • jQuery UI for the more sophisticated widgets / effects • MIT/GPL2 license • Bundled into a growing number of sites and commercial/open source products • CDN hosted by Google, Microsoft as well as jquery.com itself

  10. Enter jQuery jQuery(John Resig, 2006) • Mature: • consistently fine tuned for speed and stability (leveraging native platform strengths where possible) • resisting explosive or trendy feature creep • stewarded by a large enough user/developer base to make it unlikely to become abandonware • Aggressively cross-browser compatible, standards compliant and adaptive to trends in web technologies

  11. Example JavaScript: jQuery: $("select.swaptext").change (function() { varannot=$(this).closest('form').find('.note'); $(annot).find('div').hide(); $('#'+$(annot).attr('id')+$(this).val()).show(); }); <select class=”swaptext”> function newswap (target) { for (vari in this) { myobj = document.getElementById(this[i]);if (i != 'swapit') {myobj.style.display = 'none';} } document.getElementById (this[target]).style.display = 'block'; } Array.prototype.swapit= newswap; <select id="srchtype" onchange="swapsrch.swapit(this.options[this.selectedIndex].text);">

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