CODEWITHSUNDEEP
javascript
user9211865
user9211865

Reputation:

Javascript for loop with multiple conditions not working

I wanted to write below code with For loop having multiple conditions but it didn't work. Please point the mistake I made.

// Working as expected
bs = [false, true, false];
for (let i = 0; i < 3; i++) {
  if (bs[i]) {
    console.log('Hi', i);
  }
}

Code that is not working as expected 

// Not working as expected
bs = [false, true, false];
for (let i = 0; i < 3 && bs[i]; i++) {
  console.log('Hi', i);
}

Upvotes: 0

Views: 601

Answers (3)

Amardeep Bhowmick
Amardeep Bhowmick

Reputation: 16908

The entire for loop is exiting as the exit condition is evaluated to false due to the i < 3 && bs[i] expression. So in the first iteration itself the loop sees the false value in the array and it exits as i < 3 && bs[i] is becoming false so nothing is printed.

There is no way to skip an iteration in the exit check in the for loop, you can either use an if as per your first snippet and conditionally print or you can use continue to skip an iteration depending on the value you get from the supplied array:

const bs = [false, true, false];
for (let i = 0; i < 3; i++) {
  if(bs[i] === false){
     //skips this iteration
     continue;
  }
  console.log('Hi', i);
}

You can also use the forEach method of an array:

const bs = [false, true, false];

bs.forEach((o,i) => o !== false && console.log("Hi", i));

Upvotes: 1

nikhil.doshi
nikhil.doshi

Reputation: 35

Looks alright! The second parameter of a for loop tells the interpreter about when to stop the loop. In the first for loop, the loop continues until i reaches 3, while in the second loop, the loop immediately cuts off since the first condition returns false and indicates the interpreter to stop.

Upvotes: 1

Dennis Hackethal
Dennis Hackethal

Reputation: 14305

The second for loop stops the moment its condition evaluates to false. It's not like it skips a false value.

Since the first value in the array in false, the for loop doesn't run its body once.

Upvotes: 1

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