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.`.
22 lines
721 B
Markdown
22 lines
721 B
Markdown
### sumPower
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Returns the sum of the powers of all the numbers from `start` to `end` (both inclusive).
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Use `Array.prototype.fill()` to create an array of all the numbers in the target range, `Array.prototype.map()` and the exponent operator (`**`) to raise them to `power` and `Array.prototype.reduce()` to add them together.
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Omit the second argument, `power`, to use a default power of `2`.
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Omit the third argument, `start`, to use a default starting value of `1`.
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```js
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const sumPower = (end, power = 2, start = 1) =>
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Array(end + 1 - start)
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.fill(0)
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.map((x, i) => (i + start) ** power)
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.reduce((a, b) => a + b, 0);
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```
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```js
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sumPower(10); // 385
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sumPower(10, 3); //3025
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sumPower(10, 3, 5); //2925
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```
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