What's the difference between == and ===?

Question

My teacher said always use `===` but didn't explain why. Can someone explain with an example?

Meera Nair · Accepted Answer

`===` compares value **and** type. `==` converts types first, which gives surprising results:

```js
0 == ''        // true
'1' == 1       // true
null == undefined // true
0 === ''       // false
```

Using `===` means no hidden conversions, so your code does what it says.

1 Answer