build-es/internal/keyIterator.js


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'use strict';

import isArrayLike from 'lodash-es/isArrayLike';
import keys from 'lodash-es/keys';

export default function keyIterator(coll) {
    var i = -1;
    var len;
    if (isArrayLike(coll)) {
        len = coll.length;
        return function next() {
            i++;
            return i < len ? i : null;
        };
    } else {
        var okeys = keys(coll);
        len = okeys.length;
        return function next() {
            i++;
            return i < len ? okeys[i] : null;
        };
    }
}