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Editor to share with you the example analysis of JavaScript function definition statements, I believe that most people do not know much about it, so share this article for your reference, I hope you can learn a lot after reading this article, let's go to know it!

Function definition statement

Now let's take a look at the code:

/ / the summation function function sum (aheline b) {return aquib;}

The above code is our typical function declaration, by function followed by the function's name identifier, parentheses, and braces. For this kind of function definition, we need to display the specified function name. We can call our function through the function name during code execution. We can take a look at the following example:

Console.log (sum); / / the console outputs the source code of the sum function. At this time, the function has not yet defined function sum (aformab) {return aquib;} console.log (sum (2heli3)); / / 5

Since the function declaration has been introduced above, we have to say about the scope of the function. The function scope means that the function body of all variables declared in the function is always visible. This shows that our variable can be used before it is declared. Through this feature, we can call it declaration advance. Let's take a look at a string of code:

Var scope = "global"; function f () {console.log (scope); / / output "undefined" instead of "global" var scope = "local"; / / the variable is assigned an initial value here, but the variable itself is a defined console.log (scope) anywhere in the body of the function; / / output "local"} f (); the above code is equivalent to var scope = "global"; function f () {var scope / / declare a local variable at the top of the function, that is, declare console.log (scope) in advance; / / the variable exists and outputs "undefined" instead of "global" var scope = "local"; / / the variable assigns the initial value console.log (scope) here; / / outputs "local"} f ()

In the code, we declare all variables in the function body, and they are defined before the declaration, but they are assigned only when the variable is executed.

The above is all the contents of the article "sample Analysis of JavaScript function definition statements". Thank you for reading! I believe we all have a certain understanding, hope to share the content to help you, if you want to learn more knowledge, welcome to follow the industry information channel!

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