Is JavaScript dynamically typed?

Yes. In JavaScript a variable has no fixed type: the type belongs to the value it currently holds, and the same variable can hold a number now and a string later.

MDN puts it plainly: JavaScript is a dynamic language with dynamic types. Nothing stops you assigning a string to a variable that held a number, and typeof reports the type of the value at that moment.

For a tester this matters in two places. A value read from the page, such as textContent, is always a string, even when it looks like a number, so '7' === 7 is false. And a typo that assigns the wrong kind of value fails at run time, not before, which is one reason teams later move test code to TypeScript.

types.mjs(node)

let value = 42;
console.log(typeof value);
value = 'forty-two';
console.log(typeof value);

Output

number
string

Test yourself

You read a cart count from the DOM into a variable: const count = await badge.textContent(), which holds '5'. What happens when you check count === 5?

AI can write the test now. The job is knowing whether it checks anything. That's what the course teaches, one chapter at a time.

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Is JavaScript dynamically typed?

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