dojo.delegate¶
| Project owner: | ?– |
|---|---|
| since: | V? |
Contents
Returns a new object which “looks” to obj for properties which it does not have a value for. Optionally takes a bag of properties to seed the returned object with initially.
Introduction¶
This is a small implementation of the Boodman/Crockford delegation pattern in JavaScript. An intermediate object constructor mediates the prototype chain for the returned object, using it to delegate down to obj for property lookup when object-local lookup fails. This can be thought of similarly to ES4’s “wrap”, save that it does not act on types but rather on pure objects.
Usage¶
// Dojo 1.7+ (AMD)
require(["dojo/_base/lang", function(lang){
var myNewObject = lang.delegate(anOldObject, { myNewProperty: "value or text"});
});
// Dojo < 1.7
var myNewObject = dojo.delegate(anOldObject, { myNewProperty: "value or text"});
Examples¶
Programmatic example¶
[ Dojo 1.7+ AMD ]
require(["dojo/_base/lang", function(lang){
var anOldObject = { bar: "baz" };
var myNewObject = lang.delegate(anOldObject, { thud: "xyzzy"});
myNewObject.bar == "baz"; // delegated to anOldObject
anOldObject.thud == undefined; // by definition
myNewObject.thud == "xyzzy"; // mixed in from props
anOldObject.bar = "thonk";
myNewObject.bar == "thonk"; // still delegated to anOldObject's bar
});
[ Dojo < 1.7 ]
var anOldObject = { bar: "baz" };
var myNewObject = dojo.delegate(anOldObject, { thud: "xyzzy"});
myNewObject.bar == "baz"; // delegated to anOldObject
anOldObject.thud == undefined; // by definition
myNewObject.thud == "xyzzy"; // mixed in from props
anOldObject.bar = "thonk";
myNewObject.bar == "thonk"; // still delegated to anOldObject's bar