String Interpolate

It's a function that takes a string, a data object, and a regular expression as arguments.

• If the input string matches the regular expression, the function will return the string with the data object interpolated into it.
• However, if the input string does not match the regular expression, the function will simply return the original string unchanged.

The default regular expression is /{{([^}]+)}}/g, which matches on single curly braces. You can pass in your own regular expression if you want to match on something else.

Usage

stringInterpolate('Hello {name}!', { name: 'World' })
// => 'Hello World!'

Extending the String prototype

If you extend the String prototype, you can use the function as a method on any string like in this example:

'Hello {name}!'.interpolate({ name: 'World' })
// => 'Hello World!'

Here is how you would do it

import stringInterpolate from './stringInterpolate'

declare global {
  interface String {
    interpolate(data: { [key: string]: string }, regexp: RegExp): string
  }
}

String.prototype.interpolate = function (
  data: { [key: string]: string },
  regexp
): string {
  return stringInterpolate(String(this), data, regexp)
}

Custom regular expression

For example match on double curly braces (instead of single)

stringInterpolate('Hello {{name}}!', { name: 'World' }, /\{{([^}]+)}}/g)
// => 'Hello World!'