Is there a way to stop a for-in loop within a nested forEach function in JavaScript?

Question

Is there a way to stop a for-in loop within a nested forEach function in JavaScript?

I am facing a situation with nested loops

for (var key in params) {
  if (Array.isArray(params[key])) {
    params[key].every(function(item) {
      let value = something(item.start, item.end);
      if (value === item.start || value == item.end) {
        return false // break
      }
    })
  }
}

When I use return false to stop the inner every() function, I also want to end the outer loop. How can I achieve this? I attempted the following:

OUTER_LOOP: for (var key in params) {
  if (Array.isArray(params[key])) {
    params[key].every(function(item) {
      let value = something(item.start, item.end);
      if (value === item.start || value == item.end) {
        return false // break
        break OUTER_LOOP; // not working
      }
    })
  }
}

However, this approach does not work as expected...so how can I correctly stop both the every() function and the outer loop simultaneously?

javascript for-loop foreach break

Answer 1

Answer №1

To efficiently break out of a loop after meeting a certain condition, you can utilize the Array#some method. With this approach, you return true within some to exit the loop based on specific criteria.

for (var key in params) {
    if (Array.isArray(params[key])) {
        const
            leave = params[key].some(item => {
                let value = something(item.start, item.end);

                // To break the outer loop, the exit condition must evaluate to true/truthy
                return value === item.start || value == item.end;
            });

        if (leave) break;
    }
}

Answer 2

To efficiently break out of a loop after meeting a certain condition, you can utilize the Array#some method. With this approach, you return true within some to exit the loop based on specific criteria.

for (var key in params) {
    if (Array.isArray(params[key])) {
        const
            leave = params[key].some(item => {
                let value = something(item.start, item.end);

                // To break the outer loop, the exit condition must evaluate to true/truthy
                return value === item.start || value == item.end;
            });

        if (leave) break;
    }
}

Is there a way to stop a for-in loop within a nested forEach function in JavaScript?

Answer №1

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