array.length undefined javascript code example

Example 1: array length javascript

var numbers = [1, 2, 3, 4, 5];
var length = numbers.length;
for (var i = 0; i < length; i++) {
  numbers[i] *= 2;
}
// numbers is now [2, 4, 6, 8, 10]

Example 2: array length javascript

var arr = [10,20,30,40,50]; //An Array is defined with 5 instances

var len= arr.length;  //Now arr.length returns 5.Basically, len=5.
console.log(len); //gives 5
console.log(arr.length); //also gives 5