37 lines
761 B
Plaintext
37 lines
761 B
Plaintext
function __reduce(arr, memo, iteratee, cb) {
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if (typeof cb !== 'function') {
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if (typeof memo === 'function' && typeof iteratee === 'function') {
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cb = iteratee;
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iteratee = memo;
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memo = [];
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} else {
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throw new TypeError('expected callback to be a function');
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}
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}
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if (!Array.isArray(arr)) {
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cb(new TypeError('expected an array'));
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return;
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}
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if (typeof iteratee !== 'function') {
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cb(new TypeError('expected iteratee to be a function'));
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return;
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}
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(function next(i, acc) {
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if (i === arr.length) {
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cb(null, acc);
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return;
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}
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iteratee(acc, arr[i], function(err, val) {
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if (err) {
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cb(err);
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return;
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}
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next(i + 1, val);
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});
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})(0, memo);
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};
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