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.`.
18 lines
776 B
Markdown
18 lines
776 B
Markdown
### mask
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Replaces all but the last `num` of characters with the specified mask character.
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Use `String.prototype.slice()` to grab the portion of the characters that will remain unmasked and use `String.padStart()` to fill the beginning of the string with the mask character up to the original length.
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Omit the second argument, `num`, to keep a default of `4` characters unmasked. If `num` is negative, the unmasked characters will be at the start of the string.
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Omit the third argument, `mask`, to use a default character of `'*'` for the mask.
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```js
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const mask = (cc, num = 4, mask = '*') => `${cc}`.slice(-num).padStart(`${cc}`.length, mask);
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```
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```js
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mask(1234567890); // '******7890'
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mask(1234567890, 3); // '*******890'
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mask(1234567890, -4, '$'); // '$$$$567890'
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```
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