Created
January 6, 2019 10:30
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Example of encapsulating state with a function that return objects.
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| const makeCounter = (initVal = 0) => { | |
| let count = initVal; | |
| const get = () => count; | |
| const set = x => (count = x); | |
| const inc = () => count++; | |
| const dec = () => count--; | |
| return Object.freeze({ | |
| get, | |
| set, | |
| inc, | |
| dec, | |
| }); | |
| }; | |
| // create the counter object | |
| const myCounter = makeCounter(); | |
| // these re-assignments do nothing because object is frozen | |
| myCounter.get = null; | |
| myCounter.set = null; | |
| // let's test our counter out | |
| console.log(myCounter.get()); // 0 | |
| myCounter.set(2); | |
| console.log(myCounter.get()); // 2 | |
| myCounter.inc(); | |
| console.log(myCounter.get()); // 3 | |
| myCounter.dec(); | |
| myCounter.dec(); | |
| console.log(myCounter.get()); // 1 |
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