For loop statements in Javascript.

Using for statements

The ordinary for loop statement

• A for loop statement has the form:

  for(initialize ; expression ; increment) {
      statement;
  }

• A for loop combines the three steps of initializing, testing, and incrementing into one statement:

  <script type="text/javascript">
    var count = 0;             // initialize the condition
    // The initializing part is: count = 0  (when the loop starts)
    // The test part is     : count < 5 (if true ; execute the body statements)
    // The incrementing part is: count++  (executes for each loop)
    for (count = 0; count < 5; count++) {
      document.write("I got a hotdog !<br>");
    }
    document.write("At end Count: "+count+"<br>");
  </script>

The EMPTY for loop statement

• You can have NO Statement in a for Loop, but the use of it is rare:

  <script type="text/javascript">
    for (var count = 0; count<5;
       document.write("count: "+ count++ +"<br>"));
    // There is no statement in the body of the for loop
    ; // This is an empty statement
  </script>

The enhanced for loop statement

• A enhanced for loop (or for/in loop) statement has the form:

  for (variable in object) {
      statement;
  }

• The for/in statement provides a way to loop through the properties of an object.
• The body of the for/in loop is executed once for each property of object.
• Before the body of the loop is executed, the name of one of the object's properties is assigned to variable.

  <script type="text/javascript">
    var verbs = ["composite ", "a ", "This ",
      "using ", "index!", "is ",
      "indirect ", "string "];
    var index = [2, 5, 1, 0, 7, 3, 6, 4];
  // verbs and index are arrays, which
  // both are a kind of an object in Javascript
    for (var i in index) {
     document.write(verbs[index[i]]);
    }
  </script>