Javascript - How can I remove some objects contains on a js object according to a specified property?

Petitemo
September 18, 2023
101 views
3 votes
4 Answers

I have an object js that contains other objects like this :

const USER: {
        LANGUAGE: { 
            'editable': 1,
            'decimal': 0,
            'degree': 0,
            'master': 1,
            0: ['', '', 0],  
            1: ['', '', 1], 
        },
        LUM: { 
            'editable': 1,
            'decimal': 0,
            'degree': 0,
            'master': 0,
            0: ['', '', 0], 
            1: ['', '', 1], 
            2: ['', '', 2], 
        },
        SP: { 
            'editable': 1,
            'decimal': 0,
            'degree': 0,
            'master': 1,
            0: ['', '', 0], 
            1: ['', '', 1], 
            2: ['', '', 2], 
        },
    },
};

I want to create another object that contains only object which contains ‘master’: 1;

How can I do that?

Tags: javascript object

Answers

- Ada
- September 12, 2023 at 4:41 pm
- 0 votes
0
JavaScript has the methods Object.keys() and Array.reduce() which you can use to filter the objects based on their properties:
```
const filteredUser = Object.keys(USER).reduce((acc, key) => {
    if (USER[key].master === 1) {
        acc[key] = USER[key];
    }
    return acc;
}, {});

console.log(filteredUser);
```
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You can try the following solutions:

const filteredObjects = {};

for (const key in USER) {
    if (USER[key]['master'] === 1) {
        filteredObjects[key] = USER[key];
    }
}

console.log(filteredObjects);

or the approach using Object.keys and the array methods filter and reduce.

const filteredObjects = Object.keys(USER)
    .filter(key => USER[key]['master'] === 1)
    .reduce((result, key) => {
        result[key] = USER[key];
        return result;
    }, {});

console.log(filteredObjects);

An one-liner with Object.entries():

console.log(Object.entries(USER).reduce((r, [key, item]) => (item.master === 1 && (r[key] = item), r), {}));

<script>
const USER= {
        LANGUAGE: { 
            'editable': 1,
            'decimal': 0,
            'degree': 0,
            'master': 1,
            0: ['', '', 0],  
            1: ['', '', 1], 
        },
        LUM: { 
            'editable': 1,
            'decimal': 0,
            'degree': 0,
            'master': 0,
            0: ['', '', 0], 
            1: ['', '', 1], 
            2: ['', '', 2], 
        },
        SP: { 
            'editable': 1,
            'decimal': 0,
            'degree': 0,
            'master': 1,
            0: ['', '', 0], 
            1: ['', '', 1], 
            2: ['', '', 2], 
        },
    };
</script>

If you want more speed, remove the destructuring:

Cycles: 10000000 / Chrome/116
--------------------------------------------------------------------
Object.entries() no destructuring :  390/min  390  432  421
Object.entries()                  :  432/min 1.1x  432  458  445
Object.keys()                     :  469/min 1.2x  469  477  479
Dimava                            :  1682/min 4.3x  1726  1706  1682
--------------------------------------------------------------------
https://github.com/silentmantra/benchmark

<script benchmark="10000000">

    const USER= {
            LANGUAGE: { 
                'editable': 1,
                'decimal': 0,
                'degree': 0,
                'master': 1,
                0: ['', '', 0],  
                1: ['', '', 1], 
            },
            LUM: { 
                'editable': 1,
                'decimal': 0,
                'degree': 0,
                'master': 0,
                0: ['', '', 0], 
                1: ['', '', 1], 
                2: ['', '', 2], 
            },
            SP: { 
                'editable': 1,
                'decimal': 0,
                'degree': 0,
                'master': 1,
                0: ['', '', 0], 
                1: ['', '', 1], 
                2: ['', '', 2], 
            },
        };

// @benchmark Object.keys()
Object.keys(USER).reduce((r, key) => (USER[key].master === 1 && (r[key] = USER[key]), r), {});

// @benchmark Object.entries()
Object.entries(USER).reduce((r, [key, item]) => (item.master === 1 && (r[key] = item), r), {});

// @benchmark Object.entries() no destructuring
Object.entries(USER).reduce((r, entry) => (entry[1].master === 1 && (r[entry[0]] = entry[1]), r), {});

// @benchmark Dimava
function objectFilter(obj, filter) {
  return Object.fromEntries(
    Object.entries(obj)
      .filter(([key, value]) => filter(value, key, obj)),
  )
}

// @run
objectFilter(USER, (e) => e.master === 1)

</script>
<script src="https://cdn.jsdelivr.net/gh/silentmantra/benchmark/loader.js"></script>

/**
 * Works the same as array.filter, but with an object
 * @template O
 * @param {O} obj
 * @param { (e: O[keyof O], k: keyof O, o: O) => boolean } filter
 * @returns { Partial<O> }
 */
function objectFilter(obj, filter) {
  return Object.fromEntries(
    Object.entries(obj)
      .filter(([key, value]) => filter(value, key, obj)),
  )
}

console.log(objectFilter(USER, (e) => e.master === 1))

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Javascript – How can I remove some objects contains on a js object according to a specified property?

Answers