JS for and other loops jump out of the multilayer loop

JS for loop jumps out of the multilayer loop

var a = [1,2,3,4,5,6,7,8]; 8 numbers
var b = [11,12,13,14,15,3,16,17]; 8 numbers

Testfor ();
Console.log (' 555 ')

function Testfor () {
for (Var k=0;k<a.length;k++) {
Console.log (' 444 ');
for (Var i=0;i<a.length;i++) {
for (Var j=0;j<b.length;j++) {
if (A[i]==b[j]) {
return false;
}
Console.log (' 111 ');
}
Console.log (' 2222 ');
}
Console.log (' 333 ');
}
}

Output:
1 plays 444
8 plays 111
1 plays 222
8 plays 111
1 plays 222
5 plays 111
1 plays 555
It is visible that return jumps directly out of the multilayer loop, returning the calling method outside
Reason: JS for is not a local scope concept, the method can be a local scope
Return will jump out of the current local function and proceed to the following method

Attention:
1. Where the For loop is executed directly under the global scope without being wrapped by a method,
Will directly lead to code written in for after will never be executed;

2. In the case of logic particularly complex multilayer loops, you will encounter some methods such as iterators,
This iterator implementation is different, and there is another case that does not jump out of any loops,
The loop still continues, except the current loop if the code is not executed once, and the next time the loop starts,
The code after if is still executed

Such as:
var cc = ' xx ';

Object.keys (o). ForEach (function (key) {
var val = O[key];
if (cc = = key) {
return false;
}
Console.log (key);
});

In addition, there are
Break
Continue
Statement
After the break statement jumps out of the loop, the code after the loop resumes (exiting the loop)
The continue continue statement interrupts the iteration in the loop, if the specified condition occurs, and then resumes the next iteration in the loop. (Skip the current iteration and go to the next iteration)
These two statements can specify a label so that you can exit a specific loop
Such as
Bbq
for (Var j=0;j<a.length;j++) {
Ccc:
for (var i =0;i<a.length;i++) {
if (i==5) {
Break BBQ; Just jump out of the BBQ outer loop.
}
}
}

Or:
function Testfor () {
Bbq
for (Var k=0;k<a.length;k++) {
Console.log (' 444 ');
Ccc:
for (Var i=0;i<a.length;i++) {
Ddd:
for (Var j=0;j<b.length;j++) {
if (j = = 2) {
Break
}
Console.log (' J ' +j);
}
Console.log (' I ' +i);
}
Console.log (' K ' +k);
}
}

The DDD loop is only exited each time the loop is j==2, and the outer loop will continue to loop.

JS for and other loops jump out of the multilayer loop