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Gets the number of arguments defined for a function.




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


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.

See also

Other articles


  • Microsoft Developer Network: Article