# IsConcatSpreadableSymbol
> Concat spreadable [symbol][mdn-symbol] which specifies whether an array-like object should be flattened to its array elements during concatenation.
## Usage
```javascript
var IsConcatSpreadableSymbol = require( '@stdlib/symbol/is-concat-spreadable' );
```
#### IsConcatSpreadableSymbol
Concat spreadable [`symbol`][mdn-symbol] which specifies whether an array-like object should be flattened to its array elements during concatenation.
```javascript
var s = typeof IsConcatSpreadableSymbol;
// e.g., returns 'symbol'
```
## Notes
- The [symbol][mdn-symbol] is only supported in environments which support [symbols][mdn-symbol]. In non-supporting environments, the value is `null`.
## Examples
```javascript
var IsConcatSpreadableSymbol = require( '@stdlib/symbol/is-concat-spreadable' );
var x = [ 1, 2, 3 ];
var y = {
'length': 3,
'0': 4,
'1': 5,
'2': 6
};
y[ IsConcatSpreadableSymbol ] = true;
console.log( x.concat( y ) );
y[ IsConcatSpreadableSymbol ] = false;
console.log( x.concat( y ) );
```
[mdn-symbol]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Symbol