# replaceRange method

String replaceRange (int start, int end, String replacement)

Replaces the substring from `start` to `end` with `replacement`.

Returns a new string equivalent to:

    this.substring(0, start) + replacement + this.substring(end)

The `start` and `end` indices must specify a valid range of this string. That is `0 <= start <= end <= this.length`. If `end` is `null`, it defaults to length.

## Implementation

    String replaceRange(int start, int end, String replacement);