Function addToSet

src/utils.ts:108–145

* Add properties to a lookup table * * @param set - The set to which elements will be added. * @param array - The array containing elements to be added to the set. * @param transformCaseFunc - An optional function to transform the case of each element before adding to the set. * @returns The mo

(
  set: Record<string, boolean>,
  array: readonly unknown[],
  transformCaseFunc: ReturnType<typeof unapply<string>> = stringToLowerCase
)

 * @returns The modified set with added elements.
 */
function addToSet(
  set: Record<string, boolean>,
  array: readonly unknown[],
  transformCaseFunc: ReturnType<typeof unapply<string>> = stringToLowerCase
): Record<string, boolean> {
  if (setPrototypeOf) {
    // Make 'in' and truthy checks like Boolean(set.constructor)
    // independent of any properties defined on Object.prototype.
    // Prevent prototype setters from intercepting set as a this value.
    setPrototypeOf(set, null);
  }

  if (!arrayIsArray(array)) {
    return set;
  }

  let l = array.length;
  while (l--) {
    let element = array[l];

    if (typeof element === 'string') {
      const lcElement = transformCaseFunc(element);

      if (lcElement !== element) {
        // Config presets (e.g. tags.js, attrs.js) are immutable.
        if (!isFrozen(array)) {
          (array as unknown[])[l] = lcElement;
        }

        element = lcElement;
      }
    }

    set[element as string] = true;
  }

  return set;
}

/**
 * Clean up an array to harden against CSPP