52 lines
1.4 KiB
JavaScript
52 lines
1.4 KiB
JavaScript
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const own = {}.hasOwnProperty
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/**
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* Perform the specified action for each element in an array.
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* When `callbackFn` returns a `number`, moves to the element at that index
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* next.
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*
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* @param {unknown[]} values
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* Values to iterate over.
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* @param {(this: unknown, value: unknown, index: number, array: unknown[]) => number | void} callbackFn
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* Function called for each element.
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* Can return the `index` to move to next.
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* @param {unknown} [thisArg]
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* Optional object assigned as `this` in `callbackFn`.
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* @returns {void}
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*/
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export function arrayIterate(values, callbackFn, thisArg) {
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let index = -1
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if (!values) {
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throw new Error('Iterate requires that |this| not be ' + values)
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}
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if (!own.call(values, 'length')) {
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throw new Error('Iterate requires that |this| has a `length`')
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}
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if (typeof callbackFn !== 'function') {
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throw new TypeError('`callback` must be a function')
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}
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// The length might change, so we do not cache it.
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while (++index < values.length) {
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// Skip missing values.
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if (!(index in values)) {
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continue
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}
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const result = callbackFn.call(thisArg, values[index], index, values)
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// If `callback` returns a `number`, move `index` over to `number`.
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if (typeof result === 'number') {
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// Make sure that negative numbers do not break the loop.
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if (result < 0) {
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index = 0
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}
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index = result - 1
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}
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}
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}
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