48de4b40ee
* still call the callback when skipping duplicate file. This updates the completed flags, and so the overall "we're done" callback fires properly.
71 lines
2.6 KiB
CoffeeScript
71 lines
2.6 KiB
CoffeeScript
class @JavascriptLoader
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# Set of library functions that provide common interface for javascript loading
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# for all module types. All functionality provided by JavascriptLoader should take
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# place at module scope, i.e. don't run jQuery over entire page
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# executeModuleScripts:
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# Scan the module ('el') for "script_placeholder"s, then:
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# 1) Fetch each script from server
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# 2) Explicitly attach the script to the <head> of document
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# 3) Explicitly wait for each script to be loaded
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# 4) Return to callback function when all scripts loaded
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@executeModuleScripts: (el, callback=null) ->
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placeholders = el.find(".script_placeholder")
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if placeholders.length == 0
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callback() if callback?
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return
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# TODO: Verify the execution order of multiple placeholders
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completed = (false for i in [1..placeholders.length])
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callbackCalled = false
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# This is required for IE8 support.
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completionHandlerGeneratorIE = (index) =>
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return () ->
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if (this.readyState == 'complete' || this.readyState == 'loaded')
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#completionHandlerGenerator.call(self, index)()
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completionHandlerGenerator(index)()
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completionHandlerGenerator = (index) =>
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return () =>
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allComplete = true
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completed[index] = true
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for flag in completed
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if not flag
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allComplete = false
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break
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if allComplete and not callbackCalled
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callbackCalled = true
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callback() if callback?
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# Keep a map of what sources we're loaded from, and don't do it twice.
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loaded = {}
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placeholders.each (index, placeholder) ->
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# TODO: Check if the script already exists in DOM. If so, (1) copy it
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# into memory; (2) delete the DOM script element; (3) reappend it.
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# This would prevent memory bloat and save a network request.
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src = $(placeholder).attr("data-src")
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if src not of loaded
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loaded[src] = true
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s = document.createElement('script')
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s.setAttribute('src', src)
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s.setAttribute('type', "text/javascript")
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s.onload = completionHandlerGenerator(index)
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# s.onload does not fire in IE8; this does.
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s.onreadystatechange = completionHandlerGeneratorIE(index)
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# Need to use the DOM elements directly or the scripts won't execute
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# properly.
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$('head')[0].appendChild(s)
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else
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# just call the completion callback directly, without reloading the file
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completionHandlerGenerator(index)()
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$(placeholder).remove()
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