Cannot read property 'prototype' of undefined after upgrading to Protractor 4

Question

Recently, we've upgraded to Protractor 4.0.0 and our tests started to fail immediately with:

Error: TypeError: Cannot read property 'prototype' of undefined

Failing in onPrepare() on the following line:

protractor.ElementArrayFinder.prototype.takewhile = function(whileFn) {
   // ...
};

Here we are extending ElementArrayFinder to support takewhile function.

Looks like protractor.ElementArrayFinder is now undefined. How should we be extending ElementArrayFinder in Protractor 4?

^{I don't see anything related in the breaking changes in the changelog.}

---

Issue tracker link: Cannot read property 'prototype' of undefined (Protractor 4 upgrade problem).

Answer 1

It seems that ElementFinder and ElementArrayFinder are no longer exposed in the protractor namespace. You could simply import them with require:

var ElementFinder = require('protractor/built/element').ElementFinder;
var ElementArrayFinder = require('protractor/built/element').ElementArrayFinder;

ElementArrayFinder.prototype.takewhile = function(whileFn) {
    ...
};