8ee50178f3
Correct: `Array.from()` (it’s a static method) Incorrect: `Array.join()` (doesn’t exist; it’s a prototype method) This patch uses the common `#` syntax to denote `.prototype.`.
26 lines
1.0 KiB
Markdown
26 lines
1.0 KiB
Markdown
### pullBy
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Mutates the original array to filter out the values specified, based on a given iterator function.
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Check if the last argument provided in a function.
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Use `Array.prototype.map()` to apply the iterator function `fn` to all array elements.
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Use `Array.prototype.filter()` and `Array.prototype.includes()` to pull out the values that are not needed.
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Use `Array.prototype.length = 0` to mutate the passed in an array by resetting it's length to zero and `Array.prototype.push()` to re-populate it with only the pulled values.
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```js
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const pullBy = (arr, ...args) => {
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const length = args.length;
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let fn = length > 1 ? args[length - 1] : undefined;
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fn = typeof fn == 'function' ? (args.pop(), fn) : undefined;
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let argState = (Array.isArray(args[0]) ? args[0] : args).map(val => fn(val));
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let pulled = arr.filter((v, i) => !argState.includes(fn(v)));
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arr.length = 0;
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pulled.forEach(v => arr.push(v));
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};
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```
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```js
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var myArray = [{ x: 1 }, { x: 2 }, { x: 3 }, { x: 1 }];
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pullBy(myArray, [{ x: 1 }, { x: 3 }], o => o.x); // myArray = [{ x: 2 }]
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```
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