41 lines
1.0 KiB
Plaintext
41 lines
1.0 KiB
Plaintext
'use strict';
|
|
|
|
var callBound = require('call-bound');
|
|
var $toString = callBound('Object.prototype.toString');
|
|
var hasSymbols = require('has-symbols')();
|
|
var safeRegexTest = require('safe-regex-test');
|
|
|
|
if (hasSymbols) {
|
|
var $symToStr = callBound('Symbol.prototype.toString');
|
|
var isSymString = safeRegexTest(/^Symbol\(.*\)$/);
|
|
|
|
/** @type {(value: object) => value is Symbol} */
|
|
var isSymbolObject = function isRealSymbolObject(value) {
|
|
if (typeof value.valueOf() !== 'symbol') {
|
|
return false;
|
|
}
|
|
return isSymString($symToStr(value));
|
|
};
|
|
|
|
/** @type {import('.')} */
|
|
module.exports = function isSymbol(value) {
|
|
if (typeof value === 'symbol') {
|
|
return true;
|
|
}
|
|
if (!value || typeof value !== 'object' || $toString(value) !== '[object Symbol]') {
|
|
return false;
|
|
}
|
|
try {
|
|
return isSymbolObject(value);
|
|
} catch (e) {
|
|
return false;
|
|
}
|
|
};
|
|
} else {
|
|
/** @type {import('.')} */
|
|
module.exports = function isSymbol(value) {
|
|
// this environment does not support Symbols.
|
|
return false && value;
|
|
};
|
|
}
|