Method implicitLoopWhen

www/js/_hyperscript.esm.js:2582–2602

* Iterate over targets with a when condition, applying forward or reverse per element. * Supports async conditions transparently -- returns a Promise if any condition is async.

(targets, whenExpr, context, forwardFn, reverseFn)

   * Supports async conditions transparently -- returns a Promise if any condition is async.
   */
  implicitLoopWhen(targets, whenExpr, context, forwardFn, reverseFn) {
    var elements = [];
    this.implicitLoop(targets, function(elt) {
      elements.push(elt);
    });
    var conditions = elements.map(function(elt) {
      context.beingTested = elt;
      return whenExpr.evaluate(context);
    });
    context.beingTested = null;
    var hasPromise = conditions.some(function(c) {
      return c && typeof c.then === "function";
    });
    if (hasPromise) {
      return Promise.all(conditions).then((results) => {
        context.result = this.#applyWhenResults(elements, results, forwardFn, reverseFn);
      });
    } else {
      context.result = this.#applyWhenResults(elements, conditions, forwardFn, reverseFn);
    }
  }
  #applyWhenResults(elements, results, forwardFn, reverseFn) {
    var matched = [];
    for (var i = 0; i < elements.length; i++) {