Typescript - Why does this recursive function skips some numbers?

Question

From the server, I receive this JSON object. It represents an organigram of a company and the associated departments. I need to be able to choose a company, and with the ID of the company, I need to pass to an array of numbers the ID's of the associated departments. For that, I've created this recursive function. It works, but, skips 3 departments, which are placed within another department This is the JSON file { "cd": 1, "cd_base": 0, "nome": "EMPRESA A", "children": [ { "cd": 2, "cd_base": 1, "nome": "Departamento A", "children": [ { "cd": 4, "cd_base": 2, "nome": "Serviço A1", "children": [] }, { "cd": 15, "cd_base": 2, "nome": "Serviço A2", "children": [] } ] }, { "cd": 3, "cd_base": 1, "nome": "Departamento B", "children": [ { "cd": 7, "cd_base": 3, "nome": "Serviço B1", "children": [] } ] }, { "cd": 186, "cd_base": 1, "nome": "Departamento XX", "children": [] } ] } And this is the function in Typescript recursiveFunction(res: any): any[] { const numbers = new Array(); // to store the ID console.log('Im on ' + res.cd + ' | ' + res.nome); numbers.push(res.cd); if (res.children.length > 0) { console.log(res.cd + ' | ' + res.nome + ' has children'); res.children.forEach((row) => { numbers.push(row.cd); this.recursiveFunction(row); }); } else { console.log(res.cd + ' | ' + res.nome + ' doesn\'t have any children'); } return numbers; } And this is the return of that function to the console Im on 1 | EMPRESA A 1 | EMPRESA A has c Im on 2 | Departamento A 2 | Departamento A has children Im on 4 | Serviço A1 4 | Serviço A1 doesn't have any children Im on 15 | Serviço A2 15 | Serviço A2 doesn't have any children Im on 3 | Departamento B 3 | Departamento B has children Im on 7 | Serviço B1 7 | Serviço B1 doesn't have any children Im on 186 | Departamento XX 186 | Departamento XX doesn't have any children Then I log the numbers array and the result is 1,2,3,186 this.numbers.forEach(row => { console.log(row); }); // 1, 2, 3, 186 It adds the CD 1, 2, 3 and 186, but skips the 4, 7 and 15. All of those are a branch/node within another branch/node What am I missing? Is recursive the best way to do this? Is there a simpler way? Any help is appreciated JavaScript questions and answers, JavaScript questions pdf, JavaScript question bank, JavaScript questions and answers pdf, mcq on JavaScript pdf, JavaScript questions and solutions, JavaScript mcq Test , Interview JavaScript questions, JavaScript Questions for Interview, JavaScript MCQ (Multiple Choice Questions)

Answer 1

It's because you've defined a recursive function that returns a result, but you're not using that result. While the answer @aonepathan works, I would avoid using variables outside the scope of your function. Instead all you have to do, is to concatenate the result of the function with the current array: recursiveFunction(res: any): any[] { let numbers = new Array(); // to store the ID console.log('Im on ' + res.cd + ' | ' + res.nome); numbers.push(res.cd); if (res.children.length > 0) { console.log(res.cd + ' | ' + res.nome + ' has children'); res.children.forEach((row) => { numbers = numbers.concat(this.recursiveFunction(row)); }); } else { console.log(res.cd + ' | ' + res.nome + ' doesn\'t have any children'); } return numbers; } Another option is to pass the numbers array around to your function calls, and so you get rid of the return: recursiveFunction(res: any, numbers: any[]) { console.log('Im on ' + res.cd + ' | ' + res.nome); numbers.push(res.cd); if (res.children.length > 0) { console.log(res.cd + ' | ' + res.nome + ' has children'); res.children.forEach((row) => { this.recursiveFunction(row, numbers); }); } else { console.log(res.cd + ' | ' + res.nome + ' doesn\'t have any children'); } } The first time you'd call this, would be with a new Array: let result = new Array(); recursiveFunction(res, result); doSomething(result);