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30-seconds-of-code/snippets/shank.md
Brian Boyko efce13b1e1 shank() - array - duplicates Array.prototype.splice() except returns a new array instead of mutating in-place
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2018-09-27 14:59:50 +02:00

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shank

Has the same functionality as Array.prototype.splice(), but returning a new array instead of mutating the original array.

Use Array.slice() and Array.concat() to get a new array with the new contents after removing existing elements and/or adding new elements. Omit the second argument, index, to start at 0. Omit the third argument, delCount, to remove 0 elements. Omit the fourth argument, elements, in order to not add any new elements.

const shank = (arr, index = 0, delCount = 0, ...elements) => 
  arr.slice(0, index)
     .concat(elements)
     .concat(arr.slice(index + delCount));
const names = ['alpha', 'bravo', 'charlie'];
const namesAndDelta = shank(names, 1, 0, 'delta'); // [ 'alpha', 'delta', 'bravo', 'charlie' ]
const namesNoBravo = shank(names, 1, 1); // [ 'alpha', 'charlie' ]
console.log(names); // ['alpha', 'bravo', 'charlie']