how to iterate over nested array object in javascript

Question

I would like to know how to iterate through a nested array of objects in Javascipt? I have a sample object named obj. I want to retrieve the object based on condition 'in' is 'string' and 'out' 'number'.

// tried got stuck
const output = [];
    myList.forEach(entry => {
      Object.keys(entry).forEach(key => {
        const entity = entry[key][0];
        if (entity.in === "string" && entity.out === "number") {
          output.push(entity);
        }
      });
    });

var obj = [{
    "ston": [{
      "id": "identity1",
      "in": "string",
      "out": "number",
      "value": 10
    },{
        "id": "identity2",
        "in": "string",
        "out": "number",
        "value": 10
    }],
    "nton": [{
      "id": "identity1",
      "in": "number",
      "out": "number",
      "value": 20
    },{
      "id": "identity2",
      "in": "number",
      "out": "number",
      "value": 30
    }]
  }]

Expected Output

   [{
      "id": "identity1",
      "in": "string",
      "out": "number",
      "value": 10
    },{
        "id": "identity2",
        "in": "string",
        "out": "number",
        "value": 10
    }]

Answer 1

You can use rebuild that object to a nested array then flatten and finally filter.

var obj = [
  {
    "ston": [
      {"id": "identity1", "in": "string", "out": "number", "value": 10},
      {"id": "identity2", "in": "string", "out": "number", "value": 10}
    ],
    "nton": [
      {"id": "identity1", "in": "number", "out": "number", "value": 20},
      {"id": "identity2", "in": "number", "out": "number", "value": 30}
    ]
  }
];

const tmp = obj.map(e => Object.entries(e).map(([k, v]) => v)).flat(3)

const rs = tmp.filter(e => e.out==='number' && e.in ==='string')

console.log(rs)