@uiw/react-md-editor/src/utils/getSurroundingWord.ts

A markdown editor with preview, implemented with React.js and TypeScript.

import { TextRange } from '../commands';

export default function getSurroundingWord(text: string, position: number): TextRange {
  if (!text) throw Error("Argument 'text' should be truthy");

  const isWordDelimiter = (c: string) => c === ' ' || c.charCodeAt(0) === 10;

  // leftIndex is initialized to 0 because if selection is 0, it won't even enter the iteration
  let start = 0;
  // rightIndex is initialized to text.length because if selection is equal to text.length it won't even enter the interation
  let end = text.length;

  // iterate to the left
  for (let i = position; i - 1 > -1; i--) {
    if (isWordDelimiter(text[i - 1])) {
      start = i;
      break;
    }
  }

  // iterate to the right
  for (let i = position; i < text.length; i++) {
    if (isWordDelimiter(text[i])) {
      end = i;
      break;
    }
  }

  return { start, end };
}