JavaScript Symbol.keyFor() Method

The JavaScript Symbol.keyFor() method uses the global symbol registry to look up the key for the symbol. So it doesn't work for non-global symbols. If the symbol is not global, it won't be able to find it and return undefined.

Syntax

Parameters

Symbol(required): The symbol to find a key.

Return value

A string representing the key for the given symbol if one is found on the global registry

Browser Support

Chrome	40
Safari	9
Firefox	36
Opera	Yes

Example 1

<script>
//JavaScript to illustrate Symbol.keyFor
var i = Symbol.for("JavaTpoint");
var j = Symbol.for("Java");
document.write(Symbol.keyFor(i));
document.write("<br>");
document.write(Symbol.keyFor(j)); 
//expected output: JavaTpoint 
//Java
</script>

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Output:

JavaTpoint
Java

Example 2

<script>
//JavaScript to illustrate Symbol.keyFor
var JavaTpoint = Symbol.for('Done');
var Java   = Symbol.for('Done');
document.write(JavaTpoint === Java);
document.write("<br>");
document.write(Symbol.keyFor(JavaTpoint));
//expected output: true
//Done
</script>

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Output: