Question 177483 in Javascript Question posted in
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“How can I compare two objects in Javascript based on an attribute?”

Java script.
I have 2 arrays for example:

Array 1 [{name:'danny ro',age:14},{name:'Rose tl', age:17},{name:'Ali ga', age:15}]
Array 2 [{name:'danny',class:A},{name:'Ron', class:D}]

I want to compare only by names and to find out if array 1 has object with name that contains name from Array 2.
To my example I would get this answer :

{name:'danny',class:A}

I tried nesting loops but I’m looking for something simpler.

Tags:

2

Answers


  1. 0 
    const arr1 = [{name:'danny ro',age:14},{name:'Rose tl', age:17},{name:'Ali ga', age:15}]
const arr2 =  [{name:'danny',class:'A'},{name:'Ron', class:'D'}]

const filtered = arr2.filter(user => arr1.some(lookup => lookup.name.includes(user.name)));

console.log(filtered);
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  2. 0

    Cleaner method

    You can use Array.prototype.filter and Array.prototype.some to achieve this.

    Here’s how you could do this:

    const array1 = [
    {name:'danny ro', age:14},
    {name:'Rose tl', age:17},
    {name:'Ali ga', age:15}
];
const array2 = [
    {name:'danny', class:'A'},
    {name:'Ron', class:'D'}
];

// Create a new array 'result' that includes objects from array2 
// if the 'name' of the object in array2 is included in the 'name' property of any object in array1
const result = array2.filter(obj2 => 
    array1.some(obj1 => obj1.name.includes(obj2.name))
);

console.log(result);
// [{ "name": "danny", "class": "A" }]

    Efficient Method

    To achieve this task with optimal efficiency, specifically adhering to O(n) time complexity, a mapping needs to be created using the names from the initial array.

    Here’s how you could do this:

    const array1 = [
    {name:'danny ro', age:14},
    {name:'Rose tl', age:17},
    {name:'Ali ga', age:15}
];

const array2 = [
    {name:'danny', class:'A'},
    {name:'Ron', class:'D'}
];

// Create a name map from array1
const nameMap = {};

array1.forEach(obj => {
    const names = obj.name.split(' ');
    names.forEach(name => {
        nameMap[name] = true;
    });
});

// Filter array2 based on nameMap
const result = array2.filter(obj2 =>
    nameMap[obj2.name]
);

console.log(result);
// [{ "name": "danny", "class": "A" }]
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