用JavaScript乘2个数组

Question

I have 2 arrays

array1 = ["a","b"]
array2 = [ ["1","2","3"],["10","11","12"]]

The output I want is an array of objects

[
 {array1: a , array2: 1},
 {array1: a , array2: 2},
 {array1: a , array2: 3},

 {array1: b , array2: 10},
 {array1: b , array2: 11},
 {array1: b , array2: 12},
]

Is there a concise way to achieve this output instead of nested loops

Answer 1

It seems like you just need two loops. There are many ways to do that. A concise way is to reduce array1 and map array2 into the result within the outer loop:

 let array1 = ["a","b"] let array2 = [ ["1","2","3"],["10","11","12"]] let res = array1.reduce((arr, array1, i) => arr.concat(array2[i].map(array2 => ({array1, array2}))) , []) console.log(res) 

Answer 2

You could reduce the arrays and get the cartesian product of the outer elements of each arrays.

 function getCartesian(object) { return Object.entries(object).reduce((r, [k, v]) => { var temp = []; r.forEach(s => (Array.isArray(v) ? v : [v]).forEach(w => (w && typeof w === 'object' ? getCartesian(w) : [w]).forEach(x => temp.push(Object.assign({}, s, { [k]: x })) ) ) ); return temp; }, [{}]); } var array1 = ["a", "b"], array2 = [["1", "2", "3"], ["10", "11", "12"]], result = array1.reduce((r, a, i) => r.concat(getCartesian({ array1: a, array2: array2[i] })), []) console.log(result); 

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Answer 3

You can just use the map() method on the second array then use another map() method on the nested arrays. Finally, use the indexes to group the "nth" element from the first array with the elements from the "nth" nested array together inside an object like this:

 array1 = ["a","b"] array2 = [ ["1","2","3"],["10","11","12"]] let x = []; array2.map((e,i) => { // call function on every element in array2 with index callback e.map((f,j) => { // call function on every element in the nested arrays with index callback let obj = {}; obj["array1"] = array1[i]; obj["array2"] = f; x.push(obj); }); }); console.log(x); 

Answer 4

This is a similar approach to Marks Meyer answer, but using a forEach() instead of the reduce() .

 let array1 = ["a","b", "c"]; let array2 = [["1","2","3"], ["10","11","12"]]; let res = []; array1.forEach((x, i) => { if (array2[i]) res.push(...array2[i].map(y => ({array1: x, array2: y}))); }); console.log(res); 

Answer 5

You can use .map() and .flat() to map each element of array2 for each element of array1 then flatten the resulting array.

 const array1 = ["a","b"] const array2 = [ ["1","2","3"],["10","11","12"]] let res = array1.map((array1, i) => array2[i].map(array2 => ({array1, array2}))).flat() console.log(res)