src/editor.js
function prefixLength(text, prefix) {
  const exp = new RegExp(`^${prefix.pattern}`);
  return matchLength(text, exp);
}
function prefixLength(text, prefix) {
  const exp = new RegExp(`^${prefix.pattern}`);
  return matchLength(text, exp);
}
function prefixLength ( text , prefix ) { const exp = new RegExp ( ` ${ prefix . pattern } ` ) ; return matchLength ( text , exp ) ; }
Get prefix length.
@private
Get prefix length .