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Chapter 1: What is Javascript?

Chapter 1

What Is JavaScript?

WHAT’S IN THIS CHAPTER?

  • Review of JavaScript history
  • What JavaScript is
  • How JavaScript and ECMAScript are related
  • The different versions of JavaScript

When JavaScript first appeared in 1995, its main purpose was to handle some of the input validation that had previously been left to server-side languages such as Perl. Prior to that time, a round-trip to the server was needed to determine if a required field had been left blank or an entered value was invalid. Netscape Navigator sought to change that with the introduction of JavaScript. The capability to handle some basic validation on the client was an exciting new feature at a time when use of telephone modems was widespread. The associated slow speeds turned every trip to the server into an exercise in patience.


  

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