Nightwatch .waitForElementVisible('#primary-btn') warning : WaitForElement found 2 elements
You should try this
document.querySelectorAll("div[id='primary-btn']:nth-child(1)")
In nightwatch :
browser.waitForElementPresent("div[id='primary-btn']:nth-child(1)")
It means that you have 2 elements in you page with an identical id. While the standard impose a unique name, it is not enforced in the browser. You can verify it by executing this command in your browser:
document.querySelectorAll("[id='primary-btn']")
Or:
$x("//*[@id='primary-btn']")
So to get the expected element, you need to extend your selector with another condition. It could be for example:
'#container-id #primary-btn'