81 lines
1.3 KiB
CoffeeScript
81 lines
1.3 KiB
CoffeeScript
ok(if mySpecialVariable? then false else true)
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mySpecialVariable: false
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ok(if mySpecialVariable? then true else false)
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# Existential assignment.
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a: 5
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a: null
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a ?= 10
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b ?= 10
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ok a is 10 and b is 10
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# The existential operator.
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z: null
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x: z ? "EX"
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ok z is null and x is "EX"
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# Only evaluate once.
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counter: 0
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getNextNode: ->
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throw "up" if counter
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counter++
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ok(if getNextNode()? then true else false)
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# Existence chains, soaking up undefined properties:
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obj: {
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prop: "hello"
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}
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ok obj?.prop is "hello"
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ok obj?['prop'] is "hello"
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ok obj.prop?.length is 5
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ok obj?['prop']?['length'] is 5
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ok obj?.prop?.non?.existent?.property is undefined
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ok obj?['non']?['existent'].property is undefined
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# Soaks and caches method calls as well.
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arr: ["--", "----"]
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ok arr.pop()?.length is 4
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ok arr.pop()?.length is 2
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ok arr.pop()?.length is undefined
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ok arr[0]?.length is undefined
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ok arr.pop()?.length?.non?.existent()?.property is undefined
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# Soaks method calls safely.
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value: undefined
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result: value?.toString().toLowerCase()
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ok result is undefined
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value: 10
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result: value?.toString().toLowerCase()
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ok result is '10'
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# Safely existence test on soaks.
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result: not value?.property?
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ok result
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# Safely calls values off of non-existent variables.
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result: nothing?.value
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ok result is undefined
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