javascript – How to access nested json object inside array in react js

First of all your vendorList array is wrong.

let vendorList = [{"_id":"654d4224fb04863b8eb89200","firms":[{"_id":["65423d5c240388c1594e7b7b"],"name":["Camaro Coiled Tubing"]}]},
{"_id":"654d4224fb04863b8eb8920d","firms":[{"_id":["65423d5c240388c1594e7b82"],"name":["DANCO Coiled Tubing"]}]},
{"_id":"654d4224fb04863b8eb8921b","firms":[{"_id":["65423d5c240388c1594e7b7d"],"name":["San Joaquin Bit"]}]}]

then did the traversal same as your code,but id & name are at first index of firms so made the changes as per it.

let vendorArray = [];
vendorList.forEach((vendor) => {
    vendorArray.push({
        id: vendor.firms[0]._id,
        name: vendor.firms[0].name,
    })
})

Final output:

[
  {
    id: [ '65423d5c240388c1594e7b7b' ],
    name: [ 'Camaro Coiled Tubing' ]
  },
  {
    id: [ '65423d5c240388c1594e7b82' ],
    name: [ 'DANCO Coiled Tubing' ]
  },
  { id: [ '65423d5c240388c1594e7b7d' ], name: [ 'San Joaquin Bit' ] }
]