ActionScript 3.0 备忘录

* Point 1:

"==" 与 "==="，"!="与"!=="

trace(5 == 6);    // Displays: false
trace(6 == 6);    // Displays: true
trace(6 == "6");  // Displays: true
trace(5 == "6");  // Displays: false

trace(5 != 6);    // Displays: true
trace(6 != 6);    // Displays: false
trace(6 != "6");  // Displays: false
trace(5 != "6");  // Displays: true

trace(6 === 6);    // Displays: true
trace(6 === "6");  // Displays: false
trace(6 !== 6);    // Displays: false
trace(6 !== "6");  // Displays: true

"=="和"!="只是作值的对比，而忽略数据类型的匹配

"==="和"!=="则是先进行类型的匹配，如果类型一致，才继续进行值的对比。

《ActionScript 3.0 Cookbook》里面是这样描述===和!==的：

These first check whether the values being compared are of the same datatype 

before performing the comparison.

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* Point 2: 四种不同的可见性

private

             Properties are private when they're accessible only within the class.

public

Properties are public when they're accessible within the class as well as from instances of the class (or directly from the class reference when declared as static).

protected

Properties are protected when they're accessible only within the class and to subclasses.

internal

Properties are internal when they're accessible within the package.