How to get value from an object searched key is in string

Question

I have an object

const lead = {
  companies: [{
    schoolName: "ABC",
    education: "Graduation"
  }, {
    schoolName: "DEF",
    education: "Graduation2"
  }],
  hello: 'world',
  education: {
    graduation: 'true',
  },
  nameArray: ['hello', 'world']
}

Variable I am getting from frontend

'companies[0].schoolName'

I just have to send the value if it exists in the object

Answer 1

Here is a generic solution to walk the path of an object to get its value, or null if it does not exist:

const lead = {
  companies: [
    { schoolName: "ABC", education: "Graduation" },
    { schoolName: "DEF", education: "Graduation2" }
  ],
  hello: 'world',
  education: {
    graduation: 'true',
  },
  nameArray: ['hello', 'world']
};

function getValue(obj, path) {
  return path
  .split(/[.\[\]]/)       // split on delimiters
  .filter(Boolean)        // filter out empty items
  .reduce((acc, key) => { // reduce obj: walk the path
    acc = acc ? acc[key] : null;
    return acc;
  }, obj);
}

[
  'companies[0].schoolName',
  'companies[1].education',
  'hello',
  'does.not.exist'
].forEach(path => {
  let value = getValue(lead, path);
  console.log(path, '==>', value);
});

Output:

companies[0].schoolName ==> ABC
companies[1].education ==> Graduation2
hello ==> world
does.not.exist ==> null