JavaScript syntax: Difference between revisions

Revision as of 10:34, 26 June 2015

Revision as of 10:37, 26 June 2015

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==Functions==

A [[function (programming)|function]] is a block with a (possibly empty) parameter list that is normally given a name. A function may use local variables. If you exit the function without a return statement, the value <tt>{{mono|undefined</tt>}} is returned.

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Functions are [[first class object]]s and may be assigned to other variables.

The number of arguments given when calling a function may not necessarily correspond to the number of arguments in the function definition; a named argument in the definition that does not have a matching argument in the call will have the value <tt>{{mono|undefined</tt>}} (that can be implicitly cast to false). Within the function, the arguments may also be accessed through the <tt>{{mono|arguments</tt>}} object; this provides access to all arguments using indices (e.g. <ttcode>arguments[0], arguments[1], ... arguments[n]</ttcode>), including those beyond the number of named arguments. (While the arguments list has a <tt>.length</tt> property, it is ''not'' an instance of <tt>{{mono|Array</tt>}}; it does not have methods such as <tt>{{mono|.slice()</tt>}}, <tt>{{mono|.sort()</tt>}}, etc.)

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