Page 19 - JavaScript修炼之道

任务2 通过模块模式实现代码访问控制 5

在匿名函数中使用var关键字

(function () {
var privateField = 42;

function innerFunc() {
notSoPrivate = 43;
return notSoPrivate;
}

alert(privateField); // => 42
innerFunc();
alert(notSoPrivate); // => 43
})();
alert(typeof privateField); // => Undefined
alert(notSoPrivate); // => 43 (变量被泄露到外部)

试试这个例子：“私有属性”

var obj = (function() {
var privateField = 42;
var publicField = 'foobar';

function processInternals() { alert('Internal stuff : ' + privateField);}

function run() {
processInternals();
alert(‘Still private stuff: ’ + privateField);
alert(‘Public stuff: ’ + publicField);
}

return {
publicField: publicField,
run : run
};
})();

obj.run() // 弹出三个对话框:Internal， still private， public
obj.publicField // foobar
obj.processInternals() // Undefined
obj.privateField // Undefined