A brief introduction to the return statement in JavaScript

A brief introduction to the return statement in JavaScript_javascript skills

WBOY

Release： 2016-05-16 15:27:26

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The return statement is very important in js. It not only has the function of returning function values, but also has some special usages. Let’s briefly introduce the function of the return statement with examples.

1. Used to return control and function results:

Usually, the return statement is necessary for a function, because it is often required that the function will get an expected return value after a series of code executions, and this value is returned through the return statement, and control is returned to the calling function.

Grammar format:

return expression

The code example is as follows:

function add(){
 var a=1;
 var b=2;
 return a+b;
}
function func(){
 console.log(add())
}
func();

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In the above code, when the func() function is called, the control is held by the func function. When the add function is called again, the control is handed over to the add function, and then a value is returned and the control is handed over to func. function.

Usually return is followed by an expression, but it is not absolute, for example:

return;

In this case, the control is simply transferred to the calling function to continue execution.

Extended description:

There is nothing special about the ordinary application of the return statement. The most important thing to note is the use of return false. The event handler function returns false to prevent the occurrence of the default event.

The code example is as follows:

<!DOCTYPE html> 
<html> 
<head> 
<meta charset=" utf-8"> 
<meta name="author" content="http://www.jb51.net/" /> 
<title>脚本之家</title> 
<script type="text/javascript"> 
window.onload=function(){ 
 var olink=document.getElementById("thelink"); 
 olink.onclick=function(){
 return false
 } 
} 
</script> 
</head> 
<body> 
<a href="http://www.jb51.net" id="thelink">脚本之家</a> 
</body> 
</html>

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Clicking a link will cause an onclick event. Its default action is to point the link to the link specified by the href attribute. However, if the event handler uses return false, the default event will be prevented from occurring.

Return false can also prevent event bubbling. For details, please refer to the chapter What is the role of return false in JavaScript?.

The above introduces you to the return statement in JavaScript through specific examples. I hope you like it.