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doreydorey
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restructuring how the comparisons are made. fixes dorey#2 
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Lines changed: 361 additions & 11 deletions

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‎Makefile‎

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COFFEE = $(shell which coffee)
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watch:
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${COFFEE} -w -o ./js -c ./coffee
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build:
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${COFFEE} -o ./js -c ./coffee

‎coffee/comparison_table.coffee‎

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# log = -> console?.log?.apply(console, arguments)
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isString = (obj)->
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Object::toString.call(obj) is "[object String]"
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isObject = (obj)->
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Object::toString.call(obj) is "[object Object]"
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class ForComparison
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constructor: (@item)->
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###
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The goal here is to get a string that evaluates to the desired
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value. This string is set to object.asString
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For complicated cases which can't be passed in JSON the value
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can be passed as a string wrapped in backticks which is evaluated
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here.
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example: "`parseFloat("nan")`" means NaN.
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###
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@asString = "#{@item}"
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if isString(@item)
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if @item.length > 0 and (mtch = @item.match(/^`(.*)`$/))
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match = mtch[1]
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@item = new Function("return #{match}")()
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if isString(@item)
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@asString = JSON.stringify(@item)
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else if @item is `undefined`
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@asString = "undefined"
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else if isObject(@item)
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@asString = JSON.stringify(@item)
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else if isNaN(@item)
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@asString = "NaN"
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else
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@asString = JSON.stringify(@item)
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else if @item.length is 0
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@asString = '""'
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else if @item.toString() is "[object Object]"
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@asString = "{}"
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else if @item instanceof Array
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@asString = JSON.stringify(@item)
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testResults: (fc2, comparator="===")->
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if @asString is "{}"
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evalStr = "[#{@asString}#{comparator}#{fc2.asString}][0]"
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else
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evalStr = "#{@asString}#{comparator}#{fc2.asString}"
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[evalStr, eval(evalStr)]
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toString: ->
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@asString
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###
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The values which are strings wrapped in backticks (`) are evaluated
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before being compared.
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###
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values = [true, false, 1, 0, -1,
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"`'true'`", "`'false'`", "`'1'`", "`'0'`", "`'-1'`", "",
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"`null`", "`undefined`", "`[]`", "`{}`", [[]],
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[0], [1], "`parseFloat('nan')`"]
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# Ensure that the values going in are converted to string properly (for the table headers)
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do ->
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testRepr = (what, shouldBe)->
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fc = new ForComparison(what)
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if fc.toString() isnt shouldBe
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throw new Error("Value is not being represented correctly.")
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testRepr(true,"true")
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testRepr(false,"false")
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testRepr(1,"1")
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testRepr(0,"0")
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testRepr(-1,"-1")
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testRepr("`'true'`","\"true\"")
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testRepr("`'false'`","\"false\"")
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testRepr("`'1'`","\"1\"")
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testRepr("`'0'`","\"0\"")
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testRepr("`'-1'`","\"-1\"")
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testRepr("","\"\"")
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testRepr("`null`","null")
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testRepr("`undefined`","undefined")
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testRepr("`[]`","[]")
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testRepr("`{}`","{}")
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testRepr([[]],"[[]]")
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testRepr([0],"[0]")
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testRepr([1],"[1]")
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testRepr("`parseFloat('nan')`","NaN")
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do ->
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testEquality = (tf, item, comparator)->
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fc1 = new ForComparison(item)
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if fc1.testResults(fc1, comparator)[1] isnt tf
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throw new Error("Condition should be #{tf}")
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# easy case
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testEquality(`true==true`, "`true`", "==")
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# these two were giving incorrect values before
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testEquality(`[[]]==[[]]`, "`[[]]`", "==")
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testEquality(`[]==[]`, "`[]`", "==")
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@buildComparisonTable = (values, comparator)->
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comps = (new ForComparison(v) for v in values)
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$table = $("<table>", class: "comparisons")
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$headRow = $("<tr>").append("<td>").appendTo($table)
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for comp in comps
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$("<td>", class: "header col").html($("<span>", text: comp.asString)).appendTo($headRow)
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for valX, x in comps
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$tr = $("<tr>").appendTo($table)
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$("<td>", class: "row header").text(valX.asString).appendTo($tr)
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for valY, y in comps
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td = $("<td>", class: "cell", html: "<div>&nbsp;</div>").appendTo($tr)
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[evalStr, tf] = valX.testResults(valY, comparator)
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td.attr("title", "#{evalStr} // #{tf}")
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if tf
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td.addClass("green")
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$table
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@buildComparisonTableForIf = (values)->
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comps = (new ForComparison(v) for v in values)
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$table = $("<table>", class: "comparisons")
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for comp in comps
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$tr = $("<tr>").html($("<td>", text: comp.asString)).appendTo($table)
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$td = $("<td>", class: "cell").html($("<div>", html: "&nbsp;")).appendTo($tr)
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val = (new Function("if(#{comp.asString}){return true}else{return false}"))()
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if val
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$td.addClass("green")
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expression = " if (#{comp.asString}) { /* #{if val then 'executes' else 'does not execute'} */ } "
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$("<td>", class: "expression").html(expression).appendTo($tr)
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$table

‎index.html‎

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<link rel="stylesheet" href="simple.css" type="text/css" media="all" title="simple" charset="utf-8">
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<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.4.4/jquery.min.js" type="text/javascript" charset="utf-8"></script>
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<script src="https://ajax.googleapis.com/ajax/libs/jqueryui/1.8.9/jquery-ui.min.js" type="text/javascript" charset="utf-8"></script>
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<script src="comparison-table.js" type="text/javascript" charset="utf-8"></script>
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<script type="text/javascript" src="js/comparison_table.js"></script>
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<!-- Originally from here:
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http://blog.codekills.net/archives/89-Equality-in-JavaScript.html
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2013-Nov-11. Correcting issue where "[]===[]" was incorrectly marked as true.
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Converted from this gist:
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https://gist.github.com/761080
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-->
@@ -59,9 +61,16 @@ <h4>Moral of the story:</h4>
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</div>
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</div>
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<script type="text/javascript" charset="utf-8">
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$("#two-equals").append(EqualityTable("=="))
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$("#three-equals").append(EqualityTable("==="))
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$("#if-statement").append(EqualityTable("if-statement"))
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/*
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Strings in backticks (`) are evaluated.
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*/
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var values = [true, false, 1, 0, -1, "`'true'`", "`'false'`", "`'1'`", "`'0'`", "`'-1'`",
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"", "`null`", "`undefined`", "`[]`", "`{}`", [[]], [0], [1], "`parseFloat('nan')`"];
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buildComparisonTable(values, "==").appendTo("#two-equals")
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buildComparisonTable(values, "===").appendTo("#three-equals")
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buildComparisonTableForIf(values).appendTo("#if-statement")
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$('#tabs').tabs();
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</script>
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</body>

‎js/comparison_table.js‎

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