source: trip-planner-front/node_modules/symbol-observable/es/ponyfill.js@ ceaed42

Last change on this file since ceaed42 was 6a3a178, checked in by Ema <ema_spirova@…>, 3 years ago

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1export default function symbolObservablePonyfill(root) {
2 var result;
3 var Symbol = root.Symbol;
4
5 if (typeof Symbol === 'function') {
6 if (Symbol.observable) {
7 result = Symbol.observable;
8 } else {
9
10 if (typeof Symbol.for === 'function') {
11 // This just needs to be something that won't trample other user's Symbol.for use
12 // It also will guide people to the source of their issues, if this is problematic.
13 // META: It's a resource locator!
14 result = Symbol.for('https://github.com/benlesh/symbol-observable');
15 } else {
16 // Symbol.for didn't exist! The best we can do at this point is a totally
17 // unique symbol. Note that the string argument here is a descriptor, not
18 // an identifier. This symbol is unique.
19 result = Symbol('https://github.com/benlesh/symbol-observable');
20 }
21 try {
22 Symbol.observable = result;
23 } catch (err) {
24 // Do nothing. In some environments, users have frozen `Symbol` for security reasons,
25 // if it is frozen assigning to it will throw. In this case, we don't care, because
26 // they will need to use the returned value from the ponyfill.
27 }
28 }
29 } else {
30 result = '@@observable';
31 }
32
33 return result;
34};
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