The Symbol.toPrimitive
is a symbol that specifies a function valued property that is called to convert an object to a corresponding primitive value.
Property attributes of Symbol.toPrimitive |
|
---|---|
Writable | no |
Enumerable | no |
Configurable | no |
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"
.
Examples
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 | Status | Comment |
---|---|---|
ECMAScript 2015 (6th Edition, ECMA-262) The definition of 'Symbol.toPrimitive' in that specification. |
Standard | Initial definition. |
ECMAScript Latest Draft (ECMA-262) The definition of 'Symbol.toPrimitive' in that specification. |
Living Standard |
Browser compatibility
Feature | Chrome | Edge | Firefox | Internet Explorer | Opera | Safari |
---|---|---|---|---|---|---|
Basic support | 48 | Yes | 44 | No | Yes | Yes |
Feature | Android webview | Chrome for Android | Edge mobile | Firefox for Android | IE mobile | Opera Android | iOS Safari |
---|---|---|---|---|---|---|---|
Basic support | Yes | Yes | Yes | 44 | No | Yes | Yes |