src/sass/parse.js
function checkImportant(i) {
  const start = i;
  let l;

  if (i >= tokensLength ||
      tokens[i++].type !== TokenType.ExclamationMark) return 0;

  if (l = checkSC(i)) i += l;

  if (tokens[i].value === 'important') {
    tokens[start].importantEnd = i;
    return i - start + 1;
  } else {
    return 0;
  }
}
function checkImportant(i) {
  const start = i;
  let l;

  if (i >= tokensLength ||
      tokens[i++].type !== TokenType.ExclamationMark) return 0;

  if (l = checkSC(i)) i += l;

  if (tokens[i].value === 'important') {
    tokens[start].importantEnd = i;
    return i - start + 1;
  } else {
    return 0;
  }
}
function checkImportant ( i ) { const start = i ; let l ; if ( i >= tokensLength || tokens [ i ++ ] . type !== TokenType . ExclamationMark ) return 0 ; if ( l = checkSC ( i ) ) i += l ; if ( tokens [ i ] . value === 'important' ) { tokens [ start ] . importantEnd = i ; return i - start + 1 ; } else { return 0 ; } }
Check if token is part of `!important` word
@param {number} i Token's index number
@return {number}
Check if token is part of !important word