Name
Arguments.length — the number of arguments passed to a function
Availability
JavaScript 1.1; JScript 2; ECMAScript v1
Synopsis
arguments.length
Description
The length
property
of the Arguments object specifies the number of arguments passed to
the current function. This property is defined only within a function
body.
Note that this property specifies the number of arguments actually
passed, not the number expected. See Function.length
for the number of declared arguments. Note also that this property
does not have any of the special behavior of the
Array.length
property.
Example
// Use an Arguments object to check that correct # of args were passed function check(args) { var actual = args.length; // The actual number of arguments var expected = args.callee.length; // The expected number of arguments if (actual != expected) { // Throw exception if they don't match throw new Error("Wrong number of arguments: expected: " + expected + "; actually passed " + actual); } } // A function that demonstrates how to use the function above function f(x, y, z) { check(arguments); // Check for correct number of arguments return x + y + z; // Now do the rest of the function normally }
See Also
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