代码陷入了一系列的for循环中，我不确定为什么

Question

EDIT - I changed the code to correctly declare variables below but nothing seems to have changed

I've written code using a for-loop that has to satisfy a number of criteria before executing what's within it. The problem is that, somewhere along the way, the code is getting stuck inside one of the loops, causing the computer to crash.

I've tried breaking the loop but this doesn't seem to help.

function compareKeypoints(varifiedKeypoints) {

  outer_loop: for (i = 0; i < varifiedKeypoints.length; i++) {

    let initialKeypoint = varifiedKeypoints[i];

    for (j = 0; j < varifiedKeypoints.length; j++) {

      let comparisonKeypoint = varifiedKeypoints[j];

      if (initialKeypoint.part != comparisonKeypoint.part) {

        if (Math.abs(comparisonKeypoint.position.x - initialKeypoint.position.x) <= 20
        && Math.abs(comparisonKeypoint.position.y - initialKeypoint.position.y) <= 20) {

          if (keypointsCompatible(initialKeypoint.part, comparisonKeypoint.part)) {

            console.log("Activating part: " + initialKeypoint.part);
            console.log("Activated part: " + comparisonKeypoint.part);

            let keypointPair = {
              point_1: initialKeypoint.part,
              point_2: comparisonKeypoint.part
            }

            console.log("Pushing parts!");
            activeParts.push(keypointPair);

            console.log("breaking loop!");
            break outer_loop;

            console.log("Loop NOT broken!!");

          }
        }
      }
    }
  }

  if (activeParts.length > 0) {
    console.log(activeParts);
  }
}

function keypointsCompatible(keypoint_1, keypoint_2) {

  var outcome = true;

  if (activeParts.length > 0) {

    compatibility_loop: for (i = 0; i < activeParts.length; i++) {

      if (Object.values(activeParts[i]).includes(keypoint_1) && Object.values(activeParts[i]).includes(keypoint_2)) {

        console.log(keypoint_1 + " and " + keypoint_2 + " are not compatible because they already exist as " + activeParts[i].point_1 + " and " + activeParts[i].point_2 + " respectively");

        outcome = false;

        break compatibility_loop;

        console.log("Compatibility NOT broken!!");
      }
    }
  }

  console.log("Compatibility outcome is " + outcome);
  return outcome;
}

The code is suppose to take two values in the same array and compare them. If a number of conditions are met, including if they're a certain distance apart from one another, they will be pushed into a secondary array. If the values already appear in the secondary array, which the keypointCompatible function is suppose to determine, the loop should either continue looking for other candidates or stop before being called again. For some reason, however, the code is getting stuck within the keypointCompatible function when it detects that the values have already appeared in the secondary array and the console will repeatedly print "Compatibility is false" until the browser crashes.

Answer 1

Working Solution

Use let or const instead of var or nothing. Your issue may be related to closures and variables reused between loops. Make sure you use let or const in your loops too. for (let i=0) .

When you use let or const , the runtime will create a new instance every time the block or loop iterates. However, using var will reuse the internal allocation.

So what happens with the standard var is the multiple closures or loops each use the same instance of the variable.

Unless you want the var behavior, always use let or const .

---

Another Solution

Put a newline after the label compatibility_loop

Still Another Solution

The first function is pushing into activeParts . The second function is looping activeParts . This can go on forever, or longer than expected. Pushing into the array could possibly make the loop limit never reached. Put a log on the length of activeParts in the second function to see if it is growing out of control.

Answer 2

Your code should be OK if varifiedKeypoints.length has reasonable value. And all internal variables are declared properly!

You have two loops (this inner can start at j=i+1 to save time and multiple calculations) with few conditions inside.

function compareKeypoints(varifiedKeypoints) {

  outer_loop: for (let i = 0; i < varifiedKeypoints.length; i++) {

    let initialKeypoint = varifiedKeypoints[i];

    for (let j = i+1; j < varifiedKeypoints.length; j++) {

      let comparisonKeypoint = varifiedKeypoints[j];