Function assert

third_party/subscriptions-project/swg.js:2976–3002

* Throws an error if the first argument isn't trueish. * * Supports argument substitution into the message via %s placeholders. * * Throws an error object that has two extra properties: * - associatedElement: This is the first element provided in the var args. * It can be used for improved d

(shouldBeTrueish, message, var_args)

 * @template T
 */
function assert(shouldBeTrueish, message, var_args) {
  let firstElement;
  if (!shouldBeTrueish) {
    message = message || 'Assertion failed';
    const splitMessage = message.split('%s');
    const first = splitMessage.shift();
    let formatted = first;
    const messageArray = [];
    pushIfNonEmpty(messageArray, first);
    for (let i = 2; i < arguments.length; i++) {
      const val = arguments[i];
      if (val && val.tagName) {
        firstElement = val;
      }
      const nextConstant = splitMessage.shift();
      messageArray.push(val);
      pushIfNonEmpty(messageArray, nextConstant.trim());
      formatted += toString(val) + nextConstant;
    }
    const e = new Error(formatted);
    e.fromAssert = true;
    e.associatedElement = firstElement;
    e.messageArray = messageArray;
    throw e;
  }
  return shouldBeTrueish;
}

/**
 * @param {!Array} array