A brief analysis of the differences between break, continue and return in JavaScript

break

function myBreak() {
for(var i = 0; i < 5; i++) {
if(i == 3) {
break;
}
console.log(i);
}
}
myBreak();

Output:

0
1
2

break: Jump directly out of the current loop and start execution from outside the current loop, ignoring any other statements and loop condition tests in the loop body. It can only break out of one level of loops. If your loop is a nested loop, then you need to use break step by step according to the level of nesting.

continue

function myContinue() {
for(var i = 0; i < 5; i++) {
if(i == 3) {
continue;
}
console.log(i);
}
}
myContinue();

Output:

0
1
2
4

continue: Terminate the current loop process, it does not jump out of the loop, but continues to judge the loop conditional execution statement.

You can only end one process in the loop, but you cannot terminate the loop and continue.

return

function myReturn() {
for(var i = 0; i < 5; i++) {
if(i == 3) {
return i;
}
console.log(i);
}
}
var s = myReturn();
console.log("s: " + s);

Output:

0
1
2
s: 3

return: Exit from the current method, return to the statement of the called method, and continue execution.

Summary

1. The function of the return statement

(1) return Exit from the current method, return to the statement of the called method, and continue execution

(2) return Return a value to the caller of the method statement, the data type of the return value must be consistent with the type of the return value in the method declaration. You can use forced type conversion to make the data type consistent

(3) return When the return type is declared as void in the method description, it should be With this format, no value is returned.

2. The role of the break statement

(1) The break statement can only be used within the body of a loop and a switch statement.

(2) When break appears in the switch statement body in the loop body, its function is just to jump out of the switch statement body.

(3) When break appears in the loop body but not in the switch statement body, the current loop body will be jumped out after break is executed.

(4) In the loop structure, use the break statement to make the process jump out of the current loop body, thereby ending the current loop early

3. The function of the continue statement

(1) The general form of the continue statement is: continue;

(2) Its function is to end this loop, that is, skip the remaining unexecuted statements in the loop body, and then perform the loop condition determination again.

(3) Note: Executing the continue statement does not terminate the entire loop. In while and do-while loops, the continue statement causes the flow to jump directly to the test portion of the loop's control condition, which then determines whether the loop should continue.

(4) In the for loop, after encountering continue, skip the remaining statements in the loop body, evaluate "expression 3" in the for statement, and then perform the conditional test of "expression 2",

Finally, it is decided whether to execute the for loop based on the value of "Expression 2". Within the loop body, no matter what statement component continue is used as, it will be executed according to the above function, which is different from break