Cannot Set Property 'Innerhtml' of Null

Cannot set property 'innerHTML' of null

You have to place the hello div before the script, so that it exists when the script is loaded.

Cannot set property innerHTML of null

If You use 'getElementById', those "Id" refer to HTML Id. So, in Your HTML u should have element with id="testCurrency".
for example:

<body>
    <button onclick="addNumber(1)">
    <p> id="testCurrency"></p>
    <script type="text/javascript" src="main.js"></script>
</body>

How can I solve error Cannot set property 'innerHTML' of null

You need to close your tags. Your code can't see 'div2' because 'div' is never getting closed.

<div id='div'></div>
<div id='div2'></div>

Then, in your again function you're calling document.write which shouldn't be used after page load because it writes over anything you already had on the page. It is effectively removing your <div> tags, which is then causing an error when you're trying to access them. Plus, you're already putting that value on the page through innerHTML. Short story: remove the document.write line in the button function

Given error Uncaught TypeError: Cannot set property 'innerHTML' of null when button is clicked

The error

Uncaught TypeError: Cannot set property 'innerHTML' of null

suggests that it can't set the innerHTML property of an a null value. A null value is the result of a getElementById() query which comes up empty.

So looking at what line the error occurs you can see it can't set the innerHTML of the
result9h element. And that is because it does not exist in your HTML.

ERROR TypeError: Cannot set property 'innerHTML' of null when trying to alter InnerHtml property of a label (Typescript / HTML / Angular)

The syntax for getElementById is wrong, you only pass in the name of the id. That is why element was null.

const element: HTMLElement = document.getElementById('file') as HTMLElement;

Also, use it is a good practice to check if element exist or not , so it can be something like

 if(element)
   element.innerHTML = fileName;

Stackblitz

Cannot Set Property 'Innerhtml' of Null