函数中的“返回”，如果Lodash forEach中的语句（）

Question

function(){
    _.forEach(listOfSomething, function (something) {
      if(someCondition){
        return false
      }
    });
    return true;
}

Looks simple enough - trying to check each item for some condition, if it isn't met for any item exit out of function and return false. When loop is done without exiting, return true.

Always returns true, tried console logging, and it does hit the "return false" point.

Am I missing something obvious about how js works or is this a lodash thing?

Answer 1

What you're missing is that your return false statement is inside a different function than your return true statement. You probably want to use a different lodash method like any / some .

function(){
    return _.some(listOfSomething, function (something) {
      return someCondition;
    });
}

Answer 2

Thats because there are 2 functions, the return of the second function won't make the first function return. You should set a variable as true and change it to false if the condition is met:

function(){
    var condition = true;
    _.forEach(listOfSomething, function (something) {
      if(someCondition){
        condition = false;
        return;
      }
    });
    return condition;
}

Answer 3

Taking a quick look at it, the "return" will just return false from the inner function that is executed once for every element of the list (via the forEach), not exit the outer function

In fact, I think the forEach will keep on executing (not sure about its semantics, maybe it looks for a "false" result from the function it calls to break the loop)

but set a variable called result before the forEach to true and in the if set it to false, then at the end have a return result

that should work, but you should check the docs about that forEach to see if indeed doing a "return false" will break the loop, or if there's some break or similar command to do it (maybe _.break(); but I'm not sure what that "_" instance is)