20 lines
846 B
Markdown
20 lines
846 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.slice()` to grab the portion of the characters that need to be masked and use `String.replace()` with a regexp to replace every character with the mask character.
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Concatenate the masked characters with the remaining unmasked portion of the string.
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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 = '*') =>
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('' + cc).slice(0, -num).replace(/./g, mask) + ('' + cc).slice(-num);
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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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