lazy-concat

Lazily concat two arrays and exclude duplicate items at the joint, especially for sequential arrays.

Install

$ npm install lazy-concat

Usage

import concat from 'lazy-concat'

concat([1, 2, 3], [2, 3, 9], 9, 10)
// 2 of the second array matches the second position of the first array
// concat([1, 2, 3], [2, 3, 9]) -> [1, 2, 3, 9]
// 9 matches the last item of the previously concat item
// -> [1, 2, 3, 9]
// 10 does not match,
// so the result is [1, 2, 3, 9, 10]

const concat2 = concat.factory({
  equal: (a, b) => a.i = b.i
})

concat2([{i: 1}, {i: 2}], [{i: 2}, {i: 3}])  
// [{i: 1}, {i: 2}, {i: 3}]

concat([1, 2, 3], [1, 9])
// 1 of the second array matches the first item of the first array,
// but the match is too deep
// which is deeper than the length of the second array.
// So the match will be rejected.
// And the result is `[1, 2, 3, 1, 9]`

concat(null, [1, 2])  // it will throw

concat(...items)

• items Array<any> the first item should not be null or undefined, or it will throw an error.

Returns Array

concat.factory({equal})

• equal Function the method to match items, by default:

const equal = (a, b) => a === b

Returns Function the configured concat function.

License

MIT