> For the complete documentation index, see [llms.txt](https://docs.wirebootstrap.com/wirebootstrap/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.wirebootstrap.com/wirebootstrap/utilities/untitled.md).

# Formatting

WireBootstrap provides a number of options for string, numeric, and other type formatting.  

## String Formatting

WireBootstrap adds a string extension called `format` that allows variables inside a string expression to be replaced by values.  The variables are expressed using the numeric index position of the variables within the string in curly brackets `{}`.

```javascript
const str = "Use this {0} to format {1}".format("expression", "strings");

// Use this expression to format strings
```

## Number Formatting

Numeric values can be formatted using the `format` method with a format specification.  Valid values are *C\[N]*, *P\[N]*, *N\[N]* where *\[N]* is the number of decimal places.

The example below sets the formatting for a number to one decimal place using the `N1` parameter in the `format` function. 

```javascript
const currencyFormat = wire.format(10000.12, "N1");

// currencyFormat = 10,000.1
```

## Custom Formatting

The format method can also accept a custom function in order to format data.  

The following example formats a date field called `date_field` using the third party library [moment.js](https://momentjs.com).

```javascript
const dte = wire.format("1980-10-10", (row) => {
    return moment(row["date_field"]).format("MM-DD-YYYY");
});
```

For more on formatting, visit the [core wire](/wirebootstrap/reference/wire.md) reference page.