Javascript Replace keys within an array of objects

I have an array of objects as below

[
	{contactTypeField-0: 'Index0', firstNameField-0: '0', uniqueRowField-0: 0},
	{contactTypeField-1: 'Index1', firstNameField-1: '1', uniqueRowField-1: 0}
]

What is the best way to replace the keys i.e. I want to remove -0, -1, -2 from each of the keys. So I am expecting the output as

[
	{contactTypeField: 'Index0', firstNameField: '0', uniqueRowField: 0},
	{contactTypeField: 'Index1', firstNameField: '1', uniqueRowField: 0}
]

Is there some ES6 way to achieve this ?

You could simply use regex like this:

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const data = [
  { 'contactTypeField-0': 'Index0', 'firstNameField-0': '0', 'uniqueRowField-0': 0 },
  { 'contactTypeField-1': 'Index1', 'firstNameField-1': '1', 'uniqueRowField-1': 0 }
];

const updatedData = data.map(obj => {
  const updatedObj = {};
  Object.entries(obj).forEach(([key, value]) => {
    const newKey = key.replace(/-\d+$/, '');
    updatedObj[newKey] = value;
  });
  return updatedObj;
});

console.log(updatedData);

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You can use Array#map to transform the array of objects to a new array.

For each object, map over its entries and use String#replace to remove the required suffix (the regular expression -\d+$ matches a hyphen and one or more consecutive digits directly preceding the end of the string). Finally, use Object.fromEntries to convert the array of key-value pairs back to an object.

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const arr=[{"contactTypeField-0":"Index0","firstNameField-0":"0","uniqueRowField-0":0},{"contactTypeField-1":"Index1","firstNameField-1":"1","uniqueRowField-1":0}];
const res = arr.map(o => Object.fromEntries(Object.entries(o)
                .map(([k, v]) => [k.replace(/-\d+$/, ''), v])));
console.log(res);

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You could create a reusable function that can prune keys of an object using a "prune" function i.e. pruneFn.

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const original = [
  { 'contactTypeField-0': 'Index0', 'firstNameField-0': '0', 'uniqueRowField-0': 0 },
  { 'contactTypeField-1': 'Index1', 'firstNameField-1': '1', 'uniqueRowField-1': 0 }
];

const pruneKeys = (items, pruneFn) => items
  .map(data => Object.fromEntries(Object.entries(data)
    .map(([key, value]) => [pruneFn(key), value])));

const pruned = pruneKeys(original, (key) => key.replace(/-\d+$/, ''));

console.log(pruned);

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You could even throw an error, if a key is illegal:

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const original = [
  { 'contactTypeField-0': 'Index0', 'firstNameField-0': '0', 'uniqueRowField-0': 0 },
  { 'contactTypeField-1': 'Index1', 'firstNameField-99': '1', 'uniqueRowField-1': 0 }
];

const pruneKeys = (items, pruneFn) => items
  .map((data, index) => Object.fromEntries(Object.entries(data)
    .map(([key, value]) => [pruneFn(key, index), value])));

const pruned = pruneKeys(original, (key, expectedIndex) => {
  const [, newKey, actualIndex] = key.match(/(.+)-(\d+)$/);
  if (+actualIndex !== expectedIndex) {
    throw new Error(`Expected index: ${expectedIndex}, but received ${actualIndex} for ${key}`);
  }
  return newKey;
});

console.log(pruned);

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One more way with Object.entries and reduce

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const data = [
  {
    "contactTypeField-0": "Index0",
    "firstNameField-0": "0",
    "uniqueRowField-0": 0,
  },
  {
    "contactTypeField-1": "Index1",
    "firstNameField-1": "1",
    "uniqueRowField-1": 0,
  },
];

const res = data.map((obj) =>
  Object.entries(obj).reduce(
    (acc, [key, val]) => ({ ...acc, [key.split("-")[0]]: val }),
    {}
  )
);

console.log(res);

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