从对象数组中返回键/值对最高的对象

Question

Given an array of objects, I want to return an object with the highest values from all the objects.

let countObj = [{2:1},{2:4, 5:1},{3:3}]
let finalObj = {}
let primes = [2,3,5]
// finalObj should return {2:4, 3:3, 5:1}

I feel like there should be some way to use the primes array and reduce on the countObj to get the desired result.

primes.forEach(p => countObj.reduce((a,b) =>{
                 if (a[p]){ //if prime no. exists as key in a
                      a[p] > b[p] ? //keep key/val pair in a : replace key/val pair
                    }else{ //if new prime is not a key in a
                      a[p] = b[p]
                    }    
               },{})

I'm not sure if the logic is correct and also, I don't know how to get it to return the final object.

Answer 1

Be careful with your tests: 0 is the same as a missing value. And when using reduce , you must return the accumulator object.

I'd reduce on the objects instead of reducing on the primes:

let finalObj = countObj.reduce((f, o)=>{
    primes.forEach(k=>{
       if (k in o && !(o[k]<f[k])) f[k]=o[k];
    });
    return f;
}, {});

Answer 2

You could check if the stored value is greater than the actual value and if not, then assign the value to the result set.

 var countObj = [{ 2: 1 }, { 2: 4, 5: 1 }, { 3: 3 }], finalObj = {}; countObj.forEach(o => Object.keys(o).forEach(k => finalObj[k] > o[k] || (finalObj[k] = o[k]))); console.log(finalObj); // { 2:4, 3: 3, 5: 1 } 

With primes

 var countObj = [{ 2: 1 }, { 2: 4, 5: 1 }, { 3: 3 }], finalObj = {}, primes = [2, 3, 5] countObj.forEach(o => primes.forEach(k => k in o && (finalObj[k] > o[k] || (finalObj[k] = o[k])))); console.log(finalObj); // { 2:4, 3: 3, 5: 1 } 

Answer 3

You can use a nested foreach like this.

In this case you do not need primes[]

 let countObj = [{ 2: 1 }, { 2: 4, 5: 1 }, { 3: 3 }]; let finalObj = {}; let primes = [2, 3, 5]; countObj.forEach(function(obj) { Object.keys(obj).forEach(function(key) { var finalObjValue = finalObj[key] || 0; if(obj[key] > finalObjValue) finalObj[key] = obj[key]; }); }); console.log(finalObj);