1. IntroductionIn addition to normal mode, ECMAScript 5 includes the other mode : strict mode. It means it will make JavaScript codes execute in a more strict environment.The purposes to have strict mode are:Remove some unreasonable and parts of JavaScript syntax. Reduce some of the quirk behaviors.Remove some insecure parts of code execution. Make the execution environment more secureImprove interpret efficiency and increase the execution speedBuild foundation for future JavaScript versionStrict mode shows that JavaScript is moving toward more reasonable and more secure. Most of the mainstrea...