如何在 javascript 中将数组 object 更改为嵌套的 object

Question

I would like to know how to change array object to nested object in javascript. I have list as array object, how to convert to nested object

 function nestedobj(arrlist){ var result ={}; result.list1 = arrlist[0]; result.list2 = arrlist[1] return list; } var list= [ {id: 1, cn: "SG"}, {id: 2, cn: "TH"} ] var list1= [ {id: 1, cn: "SG"}, {id: 2, cn: "TH"}, {id: 3, cn: "MY"} ] var listobj = this.nestedobj(list); var listobj1 = this.nestedobj(list1); console.log(listobj) console.log(listobj1)

Expected Output

{
  "list1":{"id": 1, "cn": "SG"},
  "list2":{"id": 2, "cn": "TH"}
}

{
  "list1":{"id": 1, "cn": "SG"},
  "list2":{"id": 2, "cn": "TH"},
  "list3":{"id": 3, "cn": "MY"}
}

Answer 1

You can use Array#reduce method(or simple loop) to generate the object where id property or index can be used to generate the property name.

 var list = [{id: 1, cn: "SG" }, { id: 2, cn: "TH" }] var list1 = [{ id: 1, cn: "SG" }, { id: 2, cn: "TH" }, { id: 3, cn: "MY" }] function convert(arr) { // iterate over the array return arr.reduce((obj, o, i) => { // define the property obj[`list${o.id}`] = o; // or with index obj[`list${i + 1}`] = o; // return object reference for next call return obj; // set initial value as empty object to keep the result }, {}) } // or with simple loop function convert1(arr) { const result = {}; for (let o of arr) result[`list${o.id}`] = o; return result } console.log(convert(list)); console.log(convert(list1)); console.log(convert1(list)); console.log(convert1(list1));

Answer 2

// Loop an collect:

 var list = [ { id: 1, cn: "SG" }, { id: 2, cn: "TH" } ]; var list1 = [ { id: 1, cn: "SG" }, { id: 2, cn: "TH" }, { id: 3, cn: "MY" } ]; function nestedobj2(list) { let result = {}; for (const v of list) { result["list" + v.id] = v; } return result; } var listobj = nestedobj2(list); console.log("%j", listobj); listobj = nestedobj2(list1); console.log("%j", listobj); function nestedobj(list) { return list.reduce((x, data) => { x["list" + data.id] = data; return x; }, {}); } listobj = nestedobj(list); console.log("%j", listobj) listobj = nestedobj(list1); console.log("%j", listobj)

 .as-console-row {color: blue!important}

Answer 3

If the number after list is the ordinal position of the item plus one

 var nestedobj = a => Object.fromEntries(Object.entries(a).map(([k, v]) => [`list${+k+1}`, v])); var list= [ {id: 1, cn: "SG"}, {id: 2, cn: "TH"} ] var list1= [ {id: 1, cn: "SG"}, {id: 2, cn: "TH"}, {id: 3, cn: "MY"} ] var listobj = nestedobj(list); var listobj1 = nestedobj(list1); console.log(listobj) console.log(listobj1)

If however, the number after list relates to the id of the object

 var nestedobj = a => Object.fromEntries(Object.values(a).map(v => [`list${v.id}`, v])); var list= [ {id: 1, cn: "SG"}, {id: 2, cn: "TH"} ] var list1= [ {id: 1, cn: "SG"}, {id: 2, cn: "TH"}, {id: 3, cn: "MY"} ] var listobj = nestedobj(list); var listobj1 = nestedobj(list1); console.log(listobj) console.log(listobj1)