39: Programming - the real basics!

This article marks the start of the Opera web standards curriculum JavaScript section! This part of the course is designed to give you a solid grounding in the real core basics of JavaScript, with more advanced followup courses to come later. We think you'll find this useful - let us know what you think, and what you'd like to see in followup courses. This article in particular looks at the basic principles of programming, in a language-neutral fashion, as a basic first step towards learning to program in JavaScript.

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Just a style thing: Since JavaScript variables have function scope, as opposed to block scope (like C/C++, Java, etc do), I don't like for loops declaring their variable in the for statement. All your for loop examples look like:

for(var i = 0; i < 10; i++)

Instead, the "var i" should be with all the other variables at the top of the function. So:

function foo() {
  var i;
  // ...
  for (i = 0; i < 10; i++) {
    // ...
  }
  // ...
}

That most closely reflects how the language works, and might help stop bad habits forming.

1. "you are using form the context"
2. "if(b < 10 and b > 20)": did you mean "if(b < 10 && b > 20)"?

typo: undertand