Concatenate object's properties of variable length of a JavaScript object into a new property of the object

Question

I have this complicated object structure:

myObject = {
    "myObject" : [
        {
            "id" : 1,
            "parameters" : [
                {
                    "name" : "name1",
                    "special" : "xxx"
                },
                {
                    "name" : "name2",
                    "special" : "yyy"           
                }
            ]
        },
        {
            "id" : 2,
            "parameters" : [
                {
                    "name" : "name3",
                    "special" : "zzz"
                }
            ]
        },
        {
            "id" : 2,
            "parameters" : [
                {
                    "name" : "name4",
                    "special" : "ttt"
                },
                {
                    "name" : "name5",
                    "special" : "aaa"
                },
                {
                    "name" : "name6",
                    "special" : "zzz"
                }
            ]
        },
        ...
    ]
};

It consists of a array of other objects, each of them having a variable number of parameters.

My goal is to concatenate the special of parameters of each object into a new string which must be stored as new property of it.

In this case, the result should look like:

myObject = {
    "myObject" : [
        {
            "id" : 1,
            "parameters" : [
                {
                    "name" : "name1",
                    "special" : "xxx"
                },
                {
                    "name" : "name2",
                    "special" : "yyy"           
                }
            ],
            "newProp" : "xxxyyy"
        },
        {
            "id" : 2,
            "parameters" : [
                {
                    "name" : "name3",
                    "special" : "zzz"
                }
            ],
            "newProp" : "zzz"
        },
        {
            "id" : 2,
            "parameters" : [
                {
                    "name" : "name4",
                    "special" : "ttt"
                },
                {
                    "name" : "name5",
                    "special" : "aaa"
                },
                {
                    "name" : "name6",
                    "special" : "zzz"
                }
            ],
            "newProp" : "tttaaazzz"
        },
        ...
    ]
};

I tried something like this:

forEach(arr in myObject.myObject){
    arr.parameters(forEach (i in arr.parameters.special) {
    myObject.myObject = i.concat(myObject.myObject);
  })
}

obviously, it does not work. But I guess that this could be the right approach.

Any suggestions?

31piy · Accepted Answer · 2018-04-26 13:09:49Z

5

You can loop through the object using Array#forEach and then construct the string based on parameter values using Array#map and Array#join, like this:

const myObject = {"myObject":[{"id":1,"parameters":[{"name":"name1","special":"xxx"},{"name":"name2","special":"yyy"}]},{"id":2,"parameters":[{"name":"name3","special":"zzz"}]},{"id":2,"parameters":[{"name":"name4","special":"ttt"},{"name":"name5","special":"aaa"},{"name":"name6","special":"zzz"}]}]};

myObject.myObject.forEach(item => {
  item.newProp = item.parameters.map(p => p.special).join('');
});

console.log(myObject);

answered Apr 26, 2018 at 13:09

31piy

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Comments

sridhar.. · Accepted Answer · 2018-04-26 13:11:07Z

Use reduce and for Each

var myObject = {
    "myObject" : [
        {
            "id" : 1,
            "parameters" : [
                {
                    "name" : "name1",
                    "special" : "xxx"
                },
                {
                    "name" : "name2",
                    "special" : "yyy"           
                }
            ]
        },
        {
            "id" : 2,
            "parameters" : [
                {
                    "name" : "name3",
                    "special" : "zzz"
                }
            ]
        },
        {
            "id" : 2,
            "parameters" : [
                {
                    "name" : "name4",
                    "special" : "ttt"
                },
                {
                    "name" : "name5",
                    "special" : "aaa"
                },
                {
                    "name" : "name6",
                    "special" : "zzz"
                }
            ]
        }
    ]
};

myObject.myObject.forEach(arr => {
 arr.prop = arr.parameters.reduce((res,obj)=> res+obj.special, '')
})

console.log(myObject)

Mohammad Usman · Accepted Answer · 2018-04-26 13:13:56Z

1

You can use .map() and .reduce() like this:

let myObject = [{"id" : 1, "parameters" : [{ "name" : "name1", "special" : "xxx"}, { "name" : "name2", "special" : "yyy" }]}, { "id" : 2, "parameters" : [{ "name" : "name3", "special" : "zzz"}]}, {"id" : 2, "parameters" : [{ "name" : "name4", "special" : "ttt"}, { "name" : "name5", "special" : "aaa"},{ "name" : "name6", "special" : "zzz"}]}];

let result = myObject.map(
  o => (o.newProp = o['parameters'].reduce((a, o) => a + o['special'], ""), o)
);

console.log(result);

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answered Apr 26, 2018 at 13:13

Mohammad Usman

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Comments

vahdet · Accepted Answer · 2018-04-26 13:18:52Z

1

One more way is to use nested map functions:

myObject = {"myObject":[{"id":1,"parameters":[{"name":"name1","special":"xxx"},{"name":"name2","special":"yyy"}]},{"id":2,"parameters":[{"name":"name3","special":"zzz"}]},{"id":2,"parameters":[{"name":"name4","special":"ttt"},{"name":"name5","special":"aaa"},{"name":"name6","special":"zzz"}]}]};

myObject.myObject.map(x => {
  x.newProp = x.parameters.map(p => p.special).join('');
  return x;
})

console.log(myObject);

answered Apr 26, 2018 at 13:18

vahdet

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