JavaScript Symbol.isConcatSpreadable Property

The JavaScript Symbol.isConcatSpreadable it is used to configure if an object should be flattened to its array elements.

NOTE: This property spreads the array to its elements when used for concatenation.

Syntax

Parameters

No parameters.

Return value

Concatenation Result.

Browser Support

Chrome	48
Safari	Yes
Firefox	48
Opera	Yes

Example 1

<script>
//JavaScript to illustrate Symbol.isConcatSpreadable
//creating array for the concatenation
var JavaTpoint = ['Core Java', 'RDBMS', 'C'];
var A = ['Python', 'R', 'C++'];
A[Symbol.isConcatSpreadable] = true;
var Show = JavaTpoint.concat(A);
document.write(Show);
//expected output:Core Java,RDBMS,C,Python,R,C++
</script>

Test it Now

Output:

Core Java, RDBMS, C, Python, R, C++

Example 2

<script>
//JavaScript to illustrate Symbol.isConcatSpreadable
//creating array for the concatenation
var JavaTpoint = [1, 2, 3];
var A = [6,7,8];
A[Symbol.isConcatSpreadable] = true;
var Show = JavaTpoint.concat(A);
document.write(Show);
//expected output:1,2,3,6,7,8
</script>

Test it Now

Output: