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JavaScript JavaScript Loops, Arrays and Objects Simplify Repetitive Tasks with Loops Create a for Loop

Posted by Unsubscribed User
Unsubscribed User
3,436 Points

Error using `for` loop in JavaScript

The challenge is asking to create a for loop that logs number from 4-156 and log the numbers using console.log. I wrote the code attached but it keeps giving me an error. When I used the console to figure out the error I got this error message Uncaught SyntaxError: Unexpected token +=. Can you point me to the right direction?

script.js 
for (var i = 4, i = 156, i += 1) {
}
  console.log (i);
Unsubscribed User
Unsubscribed User
3,436 Points

This was helpful. Thanks!

4 Answers

Steven Parker
Steven Parker
231,236 Points
Steven Parker
Steven Parker
231,236 Points

You have a few issues here:

  • the 3 clauses of a for loop should be separated by semicolons, not commas
  • a single "=" symbol is an assignment, not a comparison operator
  • for the conditional (second) clause you probably meant to write "i <= 156"
  • if you want to log each number, the console.log statement needs to be inside the loop block
Evgeniia Mas
Evgeniia Mas
4,452 Points
Evgeniia Mas
Evgeniia Mas
4,452 Points

Sure!!!! I mentioned your name at very beginning of my post as your answer was first and than when I posted my additional notes I saw extra answer from Krishna Pratap Chouhan.

Krishna Pratap Chouhan
Krishna Pratap Chouhan
15,203 Points
Krishna Pratap Chouhan
Krishna Pratap Chouhan
15,203 Points 
for (var i = 4; i <= 156; i += 1) {
  console.log (i);
}

Three problems: replace , by ; change =156 to <=156 bring console.log inside the loop

Evgeniia Mas
Evgeniia Mas
4,452 Points
Evgeniia Mas
Evgeniia Mas
4,452 Points

I agree with Steven and would like to add that in your variant there are's no action which must be executed during the loop as the {} are empty.

Syntax of for loop is such for (i = 0; i < cars.length; i++) { text += cars[i] + "<br>"; } (according w3s example here https://www.w3schools.com/js/js_loop_for.asp) You can miss the conditions of loop, but semicolon should be. for (; i < 5; i++) { alert( i ); // 0, 1, 2 }

Even a loop for (;;) { } can be. But it is INFINITE, don't try last one)).

So in your case use for (i = 4; i < 156; i++) { console.log (i); } This loop will print in console numbers from 4 to 155, if you need to include 156, than write i < 157 at the second position.

Evgeniia Mas
Evgeniia Mas
4,452 Points
Evgeniia Mas
Evgeniia Mas
4,452 Points

or i<=156; as Krishna Pratap Chouhan wrote.

James Okrah
James Okrah
2,061 Points
James Okrah
James Okrah
2,061 Points

for (i=4; i<=156; i+=){

console.log(i); } this code still did not work. can someone help me out?

Evgeniia Mas
Evgeniia Mas
4,452 Points
Evgeniia Mas
Evgeniia Mas
4,452 Points

Did you try ? perhaps in concrete task you should use only use < only and 157 therefore. for (i = 4; i <=156; i++) { console.log (i); }

Steven Parker
Steven Parker
231,236 Points
Steven Parker
Steven Parker
231,236 Points

Your increment clause is incomplete.

Instead of "i+=" you probably intended to write "i+=1".