length-property-function-javascript.md

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length Property (Function) (JavaScript) | Microsoft Docs		01/18/2017	windows-client-threshold			devlang-javascript		language-reference	length Property	JavaScript TypeScript DHTML	Length property length property (function)	fdc8e1c9-0dac-4e1b-ba3a-11073c37ef63	15	mikejo5000	mikejo	ghogen

length Property (Function) (JavaScript)

Gets the number of arguments defined for a function.

Syntax

  
functionName.length  

Remarks

The required functionName is the name of the function.

The length property of a function is initialized by the scripting engine to the number of arguments in the function's definition when an instance of the function is created.

What happens when a function is called with a number of arguments different from the value of its length property depends on the function.

Example

The following example illustrates the use of the length property:

function ArgTest(a, b){  
    var s = "";  
  
    s += "Expected Arguments: " + ArgTest.length;  
    s += "<br />";  
    s += "Passed Arguments: " + arguments.length;  
  
    return s;  
}  
  
document.write(ArgTest(1, 2));  
  
// Output:   
// Expected Arguments: 2  
// Passed Arguments: 2  
  

Requirements

[!INCLUDEjsv2]

See Also

arguments Property (Function)
length Property (Array)
length Property (String)