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In JavaScript, a function can be created in three possible ways:
- Function as an expression
- Function as a statement
- Arrow functions
In this post, we will learn about function expressions and the function statement.
Consider the following code:
| function add(num1, num2) { | |
| return num1 + num2; | |
| } | |
| var res = add(7, 2); | |
| console.log(res); |
When you create a function as shown above, it is called a function declaration or statement. You can rewrite the code above to add a function in different ways, as shown below:
| var add = function (num1, num2) { | |
| return num1 + num2; | |
| } | |
| var res = add(7, 2); | |
| console.log(res); |
The function created above is called a function expression – in this case, an anonymous function expression. A named function expression can be created as below:
| var add = function a(num1, num2) { | |
| return num1 + num2; | |
| } | |
| var res = add(7, 2); | |
| console.log(res); |
The name of the function expression can only be used inside a function body, which is helpful in recursion. A function expression can either be a:
- Named function expression
- Anonymous function expression
The third method of creating a function is by using the Arrow function, which was introduced in ECMAScript 6. You can learn more about Arrow functions here.
Some important points about naming functions are as follows:
- A function statement cannot be created without a name
- A function expression can be created without a name, meaning you’re able to create an anonymous function
