Question 243256 in Javascript Question posted in
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Javascript – Why isn't this nested for loop working when trying to find all the combinations?

I’m trying to get all the possible combinations of pairs

const arr = [1,2,3];

const groups = [];

for (let i = 0, i < arr.length, i++) {
  for (let j = i + 1, j < arr.length, j++) {
    groups.push(arr[i] + ", " + arr[j]);
  }
}

document.body.innerHTML = groups;
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3

Answers


  1. 0

    You’ve used commas , instead of semicolons ; in the for loop definitions.
    The code should look like this:

    const arr = [1, 2, 3];

const groups = [];

for (let i = 0; i < arr.length; i++) {
  for (let j = i + 1; j < arr.length; j++) {
    groups.push(arr[i] + ", " + arr[j]);
  }
}

document.body.innerHTML = groups.join("<br>");
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  2. 0

    The code you provided has some syntax errors in the for loops. The correct syntax for a for loop is for (initialization; condition; increment). You have used commas instead of semicolons to separate the initialization, condition, and increment parts.

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  3. 0

    There are two mistakes here. The first is that the syntax is the for loop is

    for(; 😉

    and not

    for(, ,)

    Secondly, in the seond for loop, you initalized j, as

    let j = i + 1

    However, if you would like all possible combinations, then it j should be 0 instead.

    So you would have:

    for (let i = 0; i < arr.length; i++) {
  for (let j = 0; j < arr.length; j++) {
    console.log(arr[i] + ", " + arr[j]);
  }
}
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