The Symbol.toPrimitive
is a symbol that specifies a function valued property that is called to convert an object to a corresponding primitive value.
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Description
With the help of the Symbol.toPrimitive
property (used as a function value), an object can be converted to a primitive value. The function is called with a string argument hint
, which specifies the preferred type of the result primitive value. The hint
argument can be one of "number"
, "string"
, and "default"
.
Property attributes of Symbol.toPrimitive |
|
---|---|
Writable | no |
Enumerable | no |
Configurable | no |
Examples
Modifying primitive values converted from an object
Following example describes how Symbol.toPrimitive
property can modify the primitive value converted from an object.
// An object without Symbol.toPrimitive property. var obj1 = {}; console.log(+obj1); // NaN console.log(`${obj1}`); // "[object Object]" console.log(obj1 + ''); // "[object Object]" // An object with Symbol.toPrimitive property. var obj2 = { [Symbol.toPrimitive](hint) { if (hint == 'number') { return 10; } if (hint == 'string') { return 'hello'; } return true; } }; console.log(+obj2); // 10 -- hint is "number" console.log(`${obj2}`); // "hello" -- hint is "string" console.log(obj2 + ''); // "true" -- hint is "default"
Specifications
Specification |
---|
ECMAScript (ECMA-262) The definition of 'Symbol.toPrimitive' in that specification. |
Browser compatibility
Desktop | Mobile | Server | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|
toPrimitive | Chrome Full support 47 | Edge Full support 15 | Firefox Full support 44 | IE No support No | Opera Full support 34 | Safari Full support 10 | WebView Android Full support 47 | Chrome Android Full support 47 | Firefox Android Full support 44 | Opera Android Full support 34 | Safari iOS Full support 10 | Samsung Internet Android Full support 5.0 | nodejs Full support 6.0.0 |
Legend
- Full support
- Full support
- No support
- No support