How to use return statement

The return statement will terminate the execution of the function and return the value of the function, but how is the return statement used? This article will introduce to you the usage of return statement in How to use return statement.

The first thing we need to know is that every function in How to use return statement returns undefined

unless otherwise stated

For To test this, we simply create an empty function and call it:

function test(){};
test();
// undefined

As expected, when we call our function, undefined is returned in the console. (Recommended course:

How to use return statement Tutorial

)

Now we will actually specify a return value. Let's recreate our test() function, but this time include the return parameter:

function test(){
  return true;
};
test();
// true

We will find that the true value is returned.

The return statement ends function execution

We have two return statements in the test function

function test(){
  return true;
  return false;
};
test();
// true

The first return statement will immediately stop the execution of the function and returns true.

The 3rd line of code return false; is not executed.

The return statement will return a value to the callback function

We created a function double() to output twice the value

let double = function(num) {
   return num * 2;
}

Because of a The value is returned to the callback function, we can create a variable and set it equal to the function call:

let six = double(3);
// 6

The return statement ends a function

Stops immediately due to return In addition to the execution of a function, it can also be used to interrupt or end the function.

The example is as follows

let countTo = function（num）{ 
  if（typeof num！='number'）
  return false;  
  for（var i = 1; i <= num; i ++）{ 
    console.log（i）; 
  } 
}

In this example, our function countto() counts up to the number entered by the user. However, if the user does not enter a number, but instead a string, boolean, array, etc., the function will end and return false.

countTo(3);
// 1
// 2
// 3countTo('cat');
// false

This article ends here. For more exciting content, you can pay attention to other related column tutorials on the php Chinese website! ! ! ###### ###

The above is the detailed content of How to use return statement. For more information, please follow other related articles on the PHP Chinese website!