Multi variable for loop Java Script

Question

Is there any way, below code works properly.. i want 'i' to stop when the limit is reached .. without using an if condition

var a1 = [1, 2, 3, 4, 5, 6];
var a2 = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
for (var i = 0, j = 0; i < a1.length, j < a2.length; i++, j++) {
  console.log('a1: ' + '[' + i + ']' + a1[i]);
  console.log('a2: ' + a2[j]);
}

is there any special reason for using two counters with the same content? — Nina Scholz
– Nina Scholz, Commented Dec 3, 2015 at 8:44

Yeldar Kurmangaliyev · Accepted Answer · 2015-12-03 07:24:54Z

1

The second parameter of a loop should be a boolean condition.

This one

i < a1.length, j < a2.length

is actually interpreted in such way that it returns the result of i < a1.length only.

Since you want the loop to execute while both of conditions are true, combine these conditions using logical AND operator:

var a1 = [1, 2, 3, 4, 5, 6];
var a2 = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
for (var i = 0, j = 0; i < a1.length && j < a2.length; i++, j++) {
  console.log('a1: ' + '[' + i + ']' + a1[i]);
  console.log('a2: ' + a2[j]);
}

By the way, i and j are actually duplicating each other. You may use the single loop counter:

var a1 = [1, 2, 3, 4, 5, 6];
var a2 = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
for (var i = 0; i < a1.length && i < a2.length; i++) {
  console.log('a1: ' + '[' + i + ']' + a1[i]);
  console.log('a2: ' + a2[i]);
}

or even

var a1 = [1, 2, 3, 4, 5, 6];
var a2 = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10];

var minLength = Math.min(a1.length, a2.length);

for (var i = 0; i < minLength; i++) {
  console.log('a1: ' + '[' + i + ']' + a1[i]);
  console.log('a2: ' + a2[i]);
}

edited Dec 3, 2015 at 7:24

answered Dec 3, 2015 at 7:19

Yeldar Kurmangaliyev

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2 Comments

Basilin Joe Over a year ago

Thing is ,i need ' j ' to go till 10

Yeldar Kurmangaliyev Over a year ago

@CodeBean There is no convenient and proper way to do this using for loop without if condition. Moreover, there is not so much sense. However, you may implement it using while.

gurvinder372 · Accepted Answer · 2015-12-03 07:19:47Z

0

no need for if condition

var a1 = [1, 2, 3, 4, 5, 6];
var a2 = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
for (var i = 0, j = 0; i < a1.length, j < a2.length, a1[i]; i++, j++) {
  console.log('a1: ' + '[' + i + ']' + a1[i]);
  console.log('a2: ' + a2[j]);
}

answered Dec 3, 2015 at 7:19

gurvinder372

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