How do I check for an empty/undefined/null string in JavaScript?

Question

Is there a `string.Empty` in JavaScript, or is it just a case of checking for `""`?

Accepted Answer

Empty string, undefined, null, ...

To check for a truthy value:

```
if (strValue) {
    // strValue was non-empty string, true, 42, Infinity, [], ...
}
```

To check for a falsy value:

```
if (!strValue) {
    // strValue was empty string, false, 0, null, undefined, ...
}
```

Empty string (only!)

To check for exactly an empty string, compare for strict equality against `""` using the `===` operator:

```
if (strValue === "") {
    // strValue was empty string
}
```

To check for not an empty string strictly, use the `!==` operator:

```
if (strValue !== "") {
    // strValue was not an empty string
}
```

Solution