You can use map to iterate the data and check for the fieldName, if fieldName is cityId then you need to change the value and return a new object otherwise just return the same object.

Write it like this:

var data = [    {fieldName: 'title', valid: false},     {fieldName: 'description', valid: true},    {fieldName: 'cityId', valid: false},    {fieldName: 'hostDescription', valid: false},]var newData = data.map(el => {                  if(el.fieldName == 'cityId')                     return Object.assign({}, el, {valid:true})                  return el              });this.setState({ data: newData }); 

Here is a sample example - ES6

The left is the code, and the right is the output

Here is the code below

const data = [    { fieldName: 'title', valid: false },     { fieldName: 'description', valid: true },    { fieldName: 'cityId', valid: false }, // old data    { fieldName: 'hostDescription', valid: false },]const newData = data.map(obj => {  if(obj.fieldName === 'cityId') // check if fieldName equals to cityId     return {       ...obj,       valid: true,       description: 'You can also add more values here' // Example of data extra fields     }  return obj});const result = { data: newData }; console.log(result);this.setState({ data: newData });

Hope this helps,Happy Coding!

How about immutability-helper? Works very well. You're looking for the $merge command I think.

@FellowStranger: I have one (and only one) section of my redux state that is an array of objects. I use the index in the reducer to update the correct entry:

case EMIT_DATA_TYPE_SELECT_CHANGE:  return state.map( (sigmap, index) => {    if ( index !== action.payload.index ) {      return sigmap;    } else {      return update(sigmap, {$merge: {        data_type: action.payload.value      }})    }})

Frankly, this is kind of greasy, and I intend to change that part of my state object, but it does work... It doesn't sound like you're using redux but the tactic should be similar.