Target browsers: iOS 5
ECMAScript 5 is replacing ECMAScript 3.1. ECMAScript 5 provides a great enhancement to object interaction. Starting with iOS 4, Safari introduced many new ECMAScript 5 features; iOS 5 brought even greater support for ECMAScript 5.
The following are the newly introduced Object methods:
Object.seal/Object.isSealed Object.freeze/Object.isFrozen Object.preventExtensions/Object.isExtensible Function.prototype.bind
Enter the following code and test it in the browser:
/*** freeze ***/
var dog = {
eat: function () {},
hair: "black"
};
var o = Object.freeze(dog);
// test if dog is frozen
assert(Object.isFrozen(dog) === true);
// can't alter the property
dog.hair = "yellow";
// can't remove property
delete dog.hair;
// can't add new property
dog.height = "0.5m";
/*** seal ***/
var human = {
eat: function () {},
hair: "black"
};
human.hair = "blonde";
var o = Object.seal...