In a Svelte application, you will need to update the state to make your app more dynamically. To update the state, you only need to reassign the new value to your state.

<script>
	let count = 0;

	function handleClick() {
      count += 1;
	}
</script>

This reassignment will apply for every type of values. If you want to update properties of arrays or objects, you need to reassignment a new value to the property

// Update array length
numbers[numbers.length] = numbers.length + 1;

// Update object property
foo.bar = "baz";

This quote from Svelte describes exactly how updating states works

A simple rule of thumb: the name of the updated variable must appear on the left hand side of the assignment