How can you merge two arrays with identical property values in Javascript?

Question

How can you merge two arrays with identical property values in Javascript?

Is there a way to combine arrays with the same property value without using map due to different indexes?

var array1 = [
        {'label':"label1",'position':0},
        {'label':"label3",'position':2},
        {'label':"label2",'position':1},
    ];

var array2 = [
        {'label':"label1",'value':"TEXT"},
        {'label':"label2",'value':"SELECT"}
     ];

desired outcome:

var array3 = [
        {'label':"label1",'value':"TEXT",'position':0},
        {'label':"label2",'value':"SELECT", 'position':1}
     ];

Here is my attempt that is not working:

var arr3 = arr1.map(function(v, i) {
        return {
            "label": v.label,
            "position": v.position,
            "value": arr2[?].value
        }
   });

javascript arrays array-map

Answer 1

Answer №1

If you're looking to accomplish a task similar to this, you may want to consider utilizing the array#reduce method. Here's an example:

var array1 = [
        {'label':"label1",'position':0},
        {'label':"label3",'position':2},
        {'label':"label2",'position':1},
    ];

var array2 = [
        {'label':"label1",'value':"TEXT"},
        {'label':"label2",'value':"SELECT"}
     ];

var array3 = array2.reduce((arr, e) => {
  arr.push(Object.assign({}, e, array1.find(a => a.label == e.label)))
  return arr;
}, [])


console.log(array3);

Answer 2

If you're looking to accomplish a task similar to this, you may want to consider utilizing the array#reduce method. Here's an example:

var array1 = [
        {'label':"label1",'position':0},
        {'label':"label3",'position':2},
        {'label':"label2",'position':1},
    ];

var array2 = [
        {'label':"label1",'value':"TEXT"},
        {'label':"label2",'value':"SELECT"}
     ];

var array3 = array2.reduce((arr, e) => {
  arr.push(Object.assign({}, e, array1.find(a => a.label == e.label)))
  return arr;
}, [])


console.log(array3);

Answer 3

Answer №2

To find a new object, one option is to utilize a Map and verify its presence.

var array1 = [{ label: "label1", position: 0 }, { label: "label3", position: 2 }, { label: "label2", position: 1 }],
    array2 = [{ label: "label1", value: "TEXT" }, { label: "label2", value: "SELECT" }],
    map = array1.reduce((m, o) => m.set(o.label, o), new Map),
    array3 = array2.reduce((r, o) => {
        if (map.has(o.label)) {
            r.push(Object.assign({}, o, map.get(o.label)));
        }
        return r;
    }, []);

console.log(array3);

.as-console-wrapper { max-height: 100% !important; top: 0; }

Answer 4

To find a new object, one option is to utilize a Map and verify its presence.

var array1 = [{ label: "label1", position: 0 }, { label: "label3", position: 2 }, { label: "label2", position: 1 }],
    array2 = [{ label: "label1", value: "TEXT" }, { label: "label2", value: "SELECT" }],
    map = array1.reduce((m, o) => m.set(o.label, o), new Map),
    array3 = array2.reduce((r, o) => {
        if (map.has(o.label)) {
            r.push(Object.assign({}, o, map.get(o.label)));
        }
        return r;
    }, []);

console.log(array3);

.as-console-wrapper { max-height: 100% !important; top: 0; }

Answer 5

Answer №3

When it comes to determining which array(s) will have labels that are subsets of the other (if any), there is a method that accommodates the possibility of either `array1` or `array2` having labels that are not present in the other array. This method involves using `reduce` on `array1` and using `find` to locate the matching label in `array2` if it exists:

var array1 = [
  {'label':"label1",'position':0},
  {'label':"label3",'position':2},
  {'label':"label2",'position':1},
];
var array2 = [
  {'label':"label1",'value':"TEXT"},
  {'label':"label2",'value':"SELECT"}
];

const output = array1.reduce((a, { label, position }) => {
  const foundValueObj = array2.find(({ label: findLabel }) => findLabel === label);
  if (!foundValueObj) return a;
  const { value } = foundValueObj;
  a.push({ label, value, position });
  return a;
}, []);
console.log(output);

Answer 6

When it comes to determining which array(s) will have labels that are subsets of the other (if any), there is a method that accommodates the possibility of either `array1` or `array2` having labels that are not present in the other array. This method involves using `reduce` on `array1` and using `find` to locate the matching label in `array2` if it exists:

var array1 = [
  {'label':"label1",'position':0},
  {'label':"label3",'position':2},
  {'label':"label2",'position':1},
];
var array2 = [
  {'label':"label1",'value':"TEXT"},
  {'label':"label2",'value':"SELECT"}
];

const output = array1.reduce((a, { label, position }) => {
  const foundValueObj = array2.find(({ label: findLabel }) => findLabel === label);
  if (!foundValueObj) return a;
  const { value } = foundValueObj;
  a.push({ label, value, position });
  return a;
}, []);
console.log(output);

Answer 7

Answer №4

In our analysis, we make the assumption that array1 contains all the labels found in array2.

Firstly, we create a map for array2 with the keys being the labels. Then, we filter out items in array1 that have labels existing in the map. Finally, we merge the objects of the filtered array with their corresponding values from the map extracted from array2.

var array1 = [{'label':"label1",'position':0},{'label':"label3",'position':2},{'label':"label2",'position':1}];
var array2 = [{'label':"label1",'value':"TEXT"},{'label':"label2",'value':"SELECT"}];
     
let map = array2.reduce((a,{label, ...rest}) => Object.assign(a,{[label]:rest}),{});
let result = array1.filter(({label}) => map[label]).map(o => ({...o, ...map[o.label]});
console.log(result);

We can further optimize performance by replacing the filter and map functions with Array.reduce in the code snippet above.

var array1 = [{'label':"label1",'position':0},{'label':"label3",'position':2},{'label':"label2",'position':1}];
var array2 = [{'label':"label1",'value':"TEXT"},{'label':"label2",'value':"SELECT"}];
     
let map = array2.reduce((a,{label, ...rest}) => Object.assign(a,{[label]:rest}),{});
let result = array1.reduce((a,o) => {
if(map[o.label]) a.push({...o, ...map[o.label]});
return a;
}, []);
console.log(result);

Answer 8

In our analysis, we make the assumption that array1 contains all the labels found in array2.

Firstly, we create a map for array2 with the keys being the labels. Then, we filter out items in array1 that have labels existing in the map. Finally, we merge the objects of the filtered array with their corresponding values from the map extracted from array2.

var array1 = [{'label':"label1",'position':0},{'label':"label3",'position':2},{'label':"label2",'position':1}];
var array2 = [{'label':"label1",'value':"TEXT"},{'label':"label2",'value':"SELECT"}];
     
let map = array2.reduce((a,{label, ...rest}) => Object.assign(a,{[label]:rest}),{});
let result = array1.filter(({label}) => map[label]).map(o => ({...o, ...map[o.label]});
console.log(result);

We can further optimize performance by replacing the filter and map functions with Array.reduce in the code snippet above.

var array1 = [{'label':"label1",'position':0},{'label':"label3",'position':2},{'label':"label2",'position':1}];
var array2 = [{'label':"label1",'value':"TEXT"},{'label':"label2",'value':"SELECT"}];
     
let map = array2.reduce((a,{label, ...rest}) => Object.assign(a,{[label]:rest}),{});
let result = array1.reduce((a,o) => {
if(map[o.label]) a.push({...o, ...map[o.label]});
return a;
}, []);
console.log(result);

Answer 9

Answer №5

Check out Array.prototype.map() and Map for further details.

// Input.
const A = [{'label':"label1",'position':0},{'label':"label3",'position':2},{'label':"label2",'position':1}]
const B = [{'label':"label1",'value':"TEXT"},{'label':"label2",'value':"SELECT"}]

// Combine Union.
const mergeUnion = (A, B) => {
  const mapA = new Map(A.map(x => [x.label, x]))
  return B.map(y => ({...mapA.get(y.label), ...y}))
}

// Result + Verification.
const output = mergeUnion(A, B)
console.log(output)

Answer 10

Check out Array.prototype.map() and Map for further details.

// Input.
const A = [{'label':"label1",'position':0},{'label':"label3",'position':2},{'label':"label2",'position':1}]
const B = [{'label':"label1",'value':"TEXT"},{'label':"label2",'value':"SELECT"}]

// Combine Union.
const mergeUnion = (A, B) => {
  const mapA = new Map(A.map(x => [x.label, x]))
  return B.map(y => ({...mapA.get(y.label), ...y}))
}

// Result + Verification.
const output = mergeUnion(A, B)
console.log(output)

Answer 11

Answer №6

Success!

Method: Merge the entities with identical description, utilizing the Object.assign() function

var set1 = [{'description':"desc1",'position':0},{'description':"desc3",'position':2},{'description':"desc2",'position':1}];
var set2 = [{'description':"desc1",'value':"TEXT"},{'description':"desc2",'value':"SELECT"}];
var output = [];

set2.forEach(function(entity, idx){
    output.push(Object.assign({}, set1.find(function(e, i){ return e.description == entity.description }), entity));
});

console.log(output)

Answer 12

Success!

Method: Merge the entities with identical description, utilizing the Object.assign() function

var set1 = [{'description':"desc1",'position':0},{'description':"desc3",'position':2},{'description':"desc2",'position':1}];
var set2 = [{'description':"desc1",'value':"TEXT"},{'description':"desc2",'value':"SELECT"}];
var output = [];

set2.forEach(function(entity, idx){
    output.push(Object.assign({}, set1.find(function(e, i){ return e.description == entity.description }), entity));
});

console.log(output)

Answer 13

Answer №7

My knowledge of javascript is limited, but there is another way to achieve the same result.

    var array1 = [
    {'label':"label1",'position':0},
    {'label':"label3",'position':2},
    {'label':"label2",'position':1},
];

    var array2 = [
    {'label':"label1",'value':"TEXT"},
    {'label':"label2",'value':"SELECT"}
 ];
     var array3=[];
 for(var i=0;i<array1.length;i++)
    {
        for(var x=0;x<array2.length;x++)
        {       
                console.log(array1[i]['label'] == array2[x]['label']);
                if(array1[i]['label'] == array2[x]['label']){
                array3.push({label:array1[i]['label'],value:array2[x]['value'],position:array1[i]['position']});

                }
        }        
    }
    console.log(array3);

Answer 14

My knowledge of javascript is limited, but there is another way to achieve the same result.

    var array1 = [
    {'label':"label1",'position':0},
    {'label':"label3",'position':2},
    {'label':"label2",'position':1},
];

    var array2 = [
    {'label':"label1",'value':"TEXT"},
    {'label':"label2",'value':"SELECT"}
 ];
     var array3=[];
 for(var i=0;i<array1.length;i++)
    {
        for(var x=0;x<array2.length;x++)
        {       
                console.log(array1[i]['label'] == array2[x]['label']);
                if(array1[i]['label'] == array2[x]['label']){
                array3.push({label:array1[i]['label'],value:array2[x]['value'],position:array1[i]['position']});

                }
        }        
    }
    console.log(array3);

How can you merge two arrays with identical property values in Javascript?

Answer №1

Answer №2

Answer №3

Answer №4

Answer №5

Answer №6

Answer №7

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