Returns a reference to the prototype for a class of objects.
object.prototype |
Arguments
- object
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Required. The name of an object.
Remarks
Use the prototype property to provide a base set of functionality to a class of objects. New instances of an object "inherit" the behavior of the prototype assigned to that object.
All intrinsic JScript objects have a prototype property that is read-only. Functionality may be added to the prototype, as in the example, but the object may not be assigned a different prototype. However, user-defined objects may be assigned a new prototype.
The method and property lists for each intrinsic object in this language reference indicate which ones are parts of the object's prototype, and which are not.
Note |
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The prototype property of a built-in object cannot be modified when running in fast mode, the default for JScript. To compile a program from the command line that uses the prototype property, you must turn off the fast option by using /fast-. It is not safe to turn off the fast option in ASP.NET because of threading issues. |
Example
Say you want to add a method to the Array object that returns the value of the largest element of the array. To do this, declare the function, add it to Array.prototype, and then use it.
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function array_max() { var i, max = this[0]; for (i = 1; i < this.length; i++) { if (max < this[i]) max = this[i]; } return max; } Array.prototype.max = array_max; var x = new Array(1, 2, 3, 4, 5, 6); print(x.max()); |
After compiling with the /fast- option, the output of the programs is:
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6 |