Merge javascript objects in array with same key
Using lodash
var array = [{name:"foo1",value:"val1"},{name:"foo1",value:["val2","val3"]},{name:"foo2",value:"val4"}];
function mergeNames (arr) {
return _.chain(arr).groupBy('name').mapValues(function (v) {
return _.chain(v).pluck('value').flattenDeep();
}).value();
}
console.log(mergeNames(array));
2021 version
- Using
reduce
to aggregate data. - Using
logical nullish assignment
only assigns ifacc[name]
is nullish (null or undefined
). - Using
Array.isArray
to determines whether the passed value is anArray
.
var arrays = [{ name: "foo1",value: "val1" }, {name: "foo1", value: ["val2", "val3"] }, {name: "foo2",value: "val4"}];
const result = arrays.reduce((acc, {name, value}) => {
acc[name] ??= {name: name, value: []};
if(Array.isArray(value)) // if it's array type then concat
acc[name].value = acc[name].value.concat(value);
else
acc[name].value.push(value);
return acc;
}, {});
console.log(Object.values(result));
Here is another way of achieving that goal:
var array = [{
name: "foo1",
value: "val1"
}, {
name: "foo1",
value: [
"val2",
"val3"
]
}, {
name: "foo2",
value: "val4"
}];
var output = array.reduce(function(o, cur) {
// Get the index of the key-value pair.
var occurs = o.reduce(function(n, item, i) {
return (item.name === cur.name) ? i : n;
}, -1);
// If the name is found,
if (occurs >= 0) {
// append the current value to its list of values.
o[occurs].value = o[occurs].value.concat(cur.value);
// Otherwise,
} else {
// add the current item to o (but make sure the value is an array).
var obj = {
name: cur.name,
value: [cur.value]
};
o = o.concat([obj]);
}
return o;
}, []);
console.log(output);
Here is one option:-
var array = [{
name: "foo1",
value: "val1"
}, {
name: "foo1",
value: ["val2", "val3"]
}, {
name: "foo2",
value: "val4"
}];
var output = [];
array.forEach(function(item) {
var existing = output.filter(function(v, i) {
return v.name == item.name;
});
if (existing.length) {
var existingIndex = output.indexOf(existing[0]);
output[existingIndex].value = output[existingIndex].value.concat(item.value);
} else {
if (typeof item.value == 'string')
item.value = [item.value];
output.push(item);
}
});
console.dir(output);