forNN 2 IE 3 ECMA 1

This is a construction that allows repeated execution of statements, usually for a controlled number of times.

 
Example
  
var userEntry = document.forms[0].entry.value;
var oneChar;
for (var i = 0; i < userEntry.length; i++) {
    oneChar = userEntry.charAt(i);
    if (oneChar < "0" || oneChar > "9") {
        alert("The entry must be numerals only.");
    }
}