how to use a js variable in html code example

Example 1: html use js variable as text

<h1>"My number: " <span id="myText"></span></h1>

<script>

	//You can use an IIFE (Immediately Invoked Function Expression)
	(() => {
  		var number = "123";
		document.getElementById("myText").innerHTML = number;
	})();
</script>

Example 2: js variable html

<div onload="document.innerHTML(name + ' is ' + age)">

Example 3: html define javascript variable

<script>
var Number = 5;
var String = "Hi!";
var boolen1 = true;
var boolen2 = false;
var array = [11, "Hi!", true];
var object = {age:11, speach:"Hi!", likes_Bananas:true};
</script>