JS- [function declaration & function expression]

 

There are two ways-defined function: function declarations and function expressions

 

Function declarations

There is an important characteristic: the function declaration upgrade (click to see) , which means before the execution context function reads the statement, the function can be called before the function declaration

functionName();	//可以在函数声明前就调用
function functionName(){
	//your code
}

Function expression

Examples

myFun();	//报错，必须在表达式后面
var myFun=function(){
	return "aa";
}

Usage Example

var encoding=1;
var myFun;
if(encoding==1){
	myFun=function(){
		return "你好";
	}
}else{
	myFun=function(){
		return "Hello";
	}
}