# withIt

***withIt(input, function(){** // do something here with this **})***

* **The context object** is available as a receiver (*this*).
* **The return value** is the lambda result.

As *withIt* is not an extension function: the context object is passed as an argument, but inside the lambda, it's available as a receiver (*this*).

We recommend using *withIt* for calling functions on the context object when you don't need to use the returned result. In code, with can be read as "**with this object, do the following**."

```ts
const numbers = mutableListOf("one", "two", "three");

withIt(numbers, function () {
    console.log(`'withIt' is called with argument ${this}`);
    console.log(`It contains ${this.length} elements`);
});
```

You can also use withIt to introduce a helper object whose properties or functions are used for calculating a value.

```ts
const numbers = mutableListOf<string>("one", "two", "three");

const firstAndLast = withIt(numbers, function () {
    return `The first element is ${this.first()}, the last element is ${this.last()}`
});
console.debug(firstAndLast);
```


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