拆分数组

Question

I have an array of arrays that looks like this.

 const data = [ ['list1'], ['item1', '1'], ['item2', '2'], ['item3', '3'], ['item4', '4'], [' '] ['list2'], ['item1', '1'], ['item2', '2'], ['item3', '3'], ['item4', '4'], [' '] ['list3'], ['item1', '1'], ['item2', '2'], ['item3', '3'], ['item4', '4'], [' '] ] 

I need to get all of the items between the list1, list2 & list3 and the empty value to build a more structured container so that list1, list2 & list3 include the items as children. eg {

 const data2 = { 'list1': {'item1': '1', 'item2': '2', 'item3': '3', 'item4': '4'}, 'list2': {'item1': '1', 'item2': '2', 'item3': '3', 'item4': '4'}, 'list3': {'item1': '1', 'item2': '2', 'item3': '3', 'item4': '4'}, 'list4': {'item1': '1', 'item2': '2', 'item3': '3', 'item4': '4'} } 

Whats the most efficient way to query the data array to get the items between the list headers? I see lodash has a _.slice method which takes an index but I can't see a way to use the value of the array as a delimiter.

Answer 1

You could reduce the whole array by using a closure over a reference to the last object with the given key.

 var data = [['list1'], ['item1', '1'], ['item2', '2'], ['item3', '3'], ['item4', '4'], [' '], ['list2'], ['item1', '1'], ['item2', '2'], ['item3', '3'], ['item4', '4'], [' '], ['list3'], ['item1', '1'], ['item2', '2'], ['item3', '3'], ['item4', '4'], [' ']], result = data.reduce(function (ref) { return function (r, a) { if (1 in a) { ref[a[0]] = a[1]; } else if (a[0].trim()) { r[a[0]] = {}; ref = r[a[0]] } return r; }; }(undefined), {}); console.log(result); 

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Answer 2

Try this:

 const data = [ ['list1'], ['item1', '1'], ['item2', '2'], ['item3', '3'], ['item4', '4'], [' '], ['list2'], ['item1', '1'], ['item2', '2'], ['item3', '3'], ['item4', '4'], [' '], ['list3'], ['item1', '1'], ['item2', '2'], ['item3', '3'], ['item4', '4'], [' '] ]; var result = {}; var lastList = null; for (var item of data) { if (item.length == 1 && item[0] != ' ') { result[item[0]] = lastList = {}; } else if (lastList != null && item.length == 2) { lastList[item[0]] = item[1]; } } console.log(result);