What is the use of waitForPageLoad() method in Framework when our test scripts don't execute unless the page is loaded by default

Question

public void waitForPageLoad(WebDriver driver){
    while(true){
        String page_status =(String)((JavascriptExecutor)driver).executeScript("return document.readyState");
        if(page_status.equals("complete")){
            break;
        }
    }
}  

I saw people using the above method in framework to wait till page finishes the JS loading.
But why to write this method as the selenium scripts doesn't execute when we navigate to next page and the page isn't loaded completely.
I guess this is used if any action made is refreshing the page, say removing a product from the cart of a online shopping site ?
Am i correct or is there any other reason ?

Answer 1

But why to write this method as the selenium scripts doesn't execute when we navigate to next page and the page isn't loaded completely.

Ok I totally get why you feel that piece of code is trivial. Well we all know how good a tool Selenium is and we expect it should be at least wait for page load out. Unfortunately it is not that simple for Selenium, as it doesn't know if you clicked a real link which takes to new URL or link to the same page or some JS to do some rich UI stuff.

There is no way for Selenium to track the impact that a click has on the browsers' internals. It might try to poll the browser for its page-loaded status immediately after clicking, but that's open to a race condition where the browser was multitasking, hasn't quite got round to dealing with the click yet.

Hope that clarifies your query.