
# **Definition and Usage**

**map()** creates a new array from calling a function for every array element.

**map()** does not execute the function for empty elements.

**map()** does not change the original array.

## Syntax

```js
array.map(function(currentValue, index, arr), thisValue);

```

## Parameters

| Parameter    | Description                                                                                 |
| ------------ | ------------------------------------------------------------------------------------------- |
| function()   |         Required.                                                                                   |
|              |         A function to be run for each array element.                                                |
| currentValue |         Required                                                                                    |
|              |         The value of the current element.                                                           |
| index        |         Optional                                                                                    |
|              |         The index of the currennt element                                                           |
| arr          |         Optional                                                                                    |
|              |         The array of the current element.                                                           |
| thisValue    |         Optional                                                                                    |
|              |         Default value **undfined**                                       |
|              |         A value passed to the function to be used as its **this** value. |
        
## Return Value

| type     | Description                                       |
| -------- | ------------------------------------------------- |
| An array | The results of a function for each array element. |

## **Some Examples**

```js
const persons = [
  { firstname: "Malcom", lastname: "Reynolds" },
  { firstname: "Kaylee", lastname: "Frye" },
  { firstname: "Jayne", lastname: "Cobb" },
];

persons.map(getFullName);

function getFullName(item) {
  return [item.firstname, item.lastname].join(" ");
}

// ES6 Arrow function style

const getFullName = (item) => [item.firstname, item.lastname].join(" ");

// or

const noFunctionEvenNedded = persons.map((anyNameDoesNotMatter) =>
  [anyNameDoesNotMatter.firstname, anyNameDoesNotMatter.lastname].join(" ")
); // This return an array full of objects.

console.log(noFunctionEvenNedded);
```

Learn more about it [here](https://devdocs.io/cpp/).


Parameter	Description
function()	Required.
	A function to be run for each array element.
currentValue	Required
	The value of the current element.
index	Optional
	The index of the currennt element
arr	Optional
	The array of the current element.
thisValue	Optional
	Default value undfined
	A value passed to the function to be used as its this value.