JavaScript----function in-depth understanding

First, all JavaScript functions can be seen as instances of function objects.

First, the method of creating the function

1. Method of function declaration

function Sayhi () {    alert ("Hi,tuan");}

2. Methods of function expressions

var sayhi=function () {      alert ("Hi,tuan");}

The difference: the function declaration promotion in JavaScript causes the browser to parse the function declaration first, whereas the function expression method can only be created if the browser reads the line.

Second, the parameters of the function

For JavaScript, the function doesn't care if you pass in a number,string, or an array, which is treated equally.

This is because the parameters in JavaScript are saved in the arguments object.

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JavaScript----function in-depth understanding