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how to get maximum of value between multiple keys from array?

I have tried this below method for only three(not multiple) keys.

getMaxValuefromkeys(values: any[], key1: string, key2: string, key3: string) {
    var val1 = Math.max.apply(Math, values.map(function (a) { return a[key1] }));
    var val2 = Math.max.apply(Math, values.map(function (a) { return a[key2]; }));
    var val3 = Math.max.apply(Math, values.map(function (a) { return a[key2]; }));
    if (val1 >= val2 || val1 >= val3) {
        return val1;
    } else if (val2 >= val3 || val2 >= val1) {
        return val2;
    }
    return val3;
}

---

But we need to check more condition and write more codes if we use multiple keys. So I have tried these below codes

Math.max.apply(Math, values.map(function (a) { return a[key1], a[key2], a[key3]; }));
                                         // where I want to return multiple keys 

---

But it's not working. Is any single line of code available for getting max value in between multiple keys from array?

how to get maximum of value between multiple keys from array?

I have tried this below method for only three(not multiple) keys.

getMaxValuefromkeys(values: any[], key1: string, key2: string, key3: string) {
    var val1 = Math.max.apply(Math, values.map(function (a) { return a[key1] }));
    var val2 = Math.max.apply(Math, values.map(function (a) { return a[key2]; }));
    var val3 = Math.max.apply(Math, values.map(function (a) { return a[key2]; }));
    if (val1 >= val2 || val1 >= val3) {
        return val1;
    } else if (val2 >= val3 || val2 >= val1) {
        return val2;
    }
    return val3;
}

---

But we need to check more condition and write more codes if we use multiple keys. So I have tried these below codes

Math.max.apply(Math, values.map(function (a) { return a[key1], a[key2], a[key3]; }));
                                         // where I want to return multiple keys 

---

But it's not working. Is any single line of code available for getting max value in between multiple keys from array?

• javascript
• angularjs
• arrays
• angular
• typescript

Share Improve this question Follow edited Jun 23, 2017 at 11:18 Ramesh Rajendran asked Jun 23, 2017 at 10:59 Ramesh RajendranRamesh Rajendran 38.7k4949 gold badges157157 silver badges239239 bronze badges 4

• Kindly explain who's/why down voted for this question. :( – Ramesh Rajendran Commented Jun 23, 2017 at 11:28
• 2 I don't know if this is the reason, but perhaps the question seems basic for a user of your reputation. I'm not saying that it is, or that it's a legit reason for downvoting, only that from my experience sometimes downvotes, in as much as some of them make sense, are on occasion related to reputation in relation to content, as well as just content itself. (I did not downvote and I very rarely do, but I know that others are less reticent). Or maybe someone lost their keys (I don't find this reason for voting funny, but I know it's munity accepted as being funny). – Peter Carter Commented Jun 23, 2017 at 11:36
• @PeterDavidCarter ! it's a large ment than below answers :p – Ramesh Rajendran Commented Jun 23, 2017 at 11:57
• 1 Yeah, it's probably a good question in that it's got a lot of answers so probably produced useful content for the munity. I think it's fine. meta.stackexchange./questions/215379/… contains the answer I was refering to when referencing lost keys. (My formal training was first in literature so I have a tendency to ramble on ;)). – Peter Carter Commented Jun 23, 2017 at 11:59

Add a ment  | 

3 Answers 3

Sorted by: Reset to default 7

Array#map each object to it's maximum value, then find the maximum of the array:

var values = [{ a: 4, b: 3 }, { a: 2, b: 8 }, { a: 1, b: 2 }];

var key1 = 'a', key2 = 'b';

var result = Math.max.apply(Math, values.map(function (a) { return Math.max(a[key1], a[key2]); }));

console.log(result);

If you want something more flexible that can accept multiple keys:

var values = [{ a: 4, b: 3, c: 23 }, { a: 2, b: 28, c: 13 }, { a: 1, b: 2, c: 1 }];

function getMaxOfKeys(values, keys) {
  return Math.max.apply(Math, values.map(function(obj) {
    return Math.max.apply(Math, keys.map(function(key) {
      return obj[key];
    }));
  }));
}

// or the ES6 equivalent

const getMaxOfKeysES6 = (values, keys) => 
  Math.max(...values.map(
    (obj) => 
      Math.max(...keys.map((key) => obj[key]))
    )
  );

console.log(getMaxOfKeys(values, ['a', 'b', 'c']));
console.log(getMaxOfKeysES6(values, ['a', 'b', 'c']));

(plain ES6 - I don't do TypeScript)

Given your object values and a set of keys that you wish to pare, e.g.:

let values = [
   { key1: 2, key2: 3, key3: 0 },
   { key1: 10, key2: 0, key3: 5 }
];

then for each key, find the maximal value within each object and return that as an array, and then find the maximal value of that array.

function getMaxValuefromkeys(values, ...keys) {
    return Math.max(...keys.map(key => Math.max(...values.map(o => o[key]))));
}

with usage:

let max = getMaxValuefromkeys(values, 'key1', 'key2', 'key3');

or given an array of keys:

let max = getMaxValuefromkeys(values, ...keys);

Math.max.apply(Math, values.map(function (a) { return Math.max(a[key1],a[key2]) }));

Note that

return a,b;

Is the ma operator , so actually it just returns b.

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