Function toPrimitive

lib/web/polyfill.js:793–798

(it)

    } return +it;
  }
  function toPrimitive(it){
    var fn, val;
    if(isFunction(fn = it.valueOf) && !isObject(val = fn.call(it)))return val;
    if(isFunction(fn = it[TO_STRING]) && !isObject(val = fn.call(it)))return val;
    throw TypeError("Can't convert object to number");
  }
  Number = function Number(it){
    return this instanceof Number ? new _Number(toNumber(it)) : toNumber(it);
  };