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# Comments

If needed, you can add comments to a program. Comments are used to explain programs.
They help us humans to understand programs. Computers ignore comments.

In JavaScript there are two ways to write comments: Line comments are introduced with

In JavaScript there are two ways to write comments: Line comments are introduced with

`//`

and are valid until the end of the line.
Block comments start with `/*`

and end with `*/`

.
Any text in between is a comment.
```
// That's a line comment.
// This line comment
// covers 2 lines.
/* That's a block comment. */
/* This block comment
covers 2 lines. */
/**
* This is also a block comment.
* The additional stars between
* the beginning and the end of the
* block comment are only for decoration.
*/
```

Block comments are often used to explain functions. Line comments explain the code flow.
```
/**
* Checks whether a string contains
* any characters other than spaces.
*/
function isBlank(string) {
// The method trim() removes spaces at
// the beginning and the end of a string.
let trimmedString = string.trim();
return trimmedString.length === 0;
}
```

Comments can't be checked with the tests used here.
It follows a task where you have to apply much of what you have learned so far.## Exercise

Write a function

Example:

`median`

that takes an array of ascending numbers and returns the
median of that numbers.Example:

`median([1, 2, 10])`

should return `2`

and `median([1, 2, 10, 100])`

should return
`6`

.
+ Hint

The median of a sorted series of numbers is the value in the middle.
If the number of values is even, the median is the mean of the two middle numbers.