javascript - Applying a conditional filter to get unique values on JSON array

Javascript - Applying a conditional filter to get unique values on JSON array

To apply a conditional filter to get unique values from a JSON array in JavaScript, you can use the filter() method along with the includes() method or create a lookup object to filter out duplicates. Here's how you can do it:

  1. Using Filter and Includes:

    // Example JSON array const jsonArray = [ { id: 1, name: 'John' }, { id: 2, name: 'Jane' }, { id: 1, name: 'John' }, // Duplicate { id: 3, name: 'Bob' }, { id: 4, name: 'Alice' }, { id: 3, name: 'Bob' } // Duplicate ]; // Apply filter to get unique values based on 'id' const uniqueArray = jsonArray.filter((item, index, array) => array.findIndex(t => t.id === item.id) === index ); console.log(uniqueArray);

    This will output:

    [ { id: 1, name: 'John' }, { id: 2, name: 'Jane' }, { id: 3, name: 'Bob' }, { id: 4, name: 'Alice' } ]

  2. Using Lookup Object:

    // Example JSON array const jsonArray = [ { id: 1, name: 'John' }, { id: 2, name: 'Jane' }, { id: 1, name: 'John' }, // Duplicate { id: 3, name: 'Bob' }, { id: 4, name: 'Alice' }, { id: 3, name: 'Bob' } // Duplicate ]; // Create a lookup object to filter out duplicates const lookup = {}; const uniqueArray = jsonArray.filter(item => { if (!lookup[item.id]) { lookup[item.id] = true; return true; } return false; }); console.log(uniqueArray);

    This will output the same result as the previous approach.

Both methods iterate over the JSON array and filter out duplicate objects based on a condition. The first method uses the filter() method along with findIndex() to find the first occurrence of each unique value. The second method uses a lookup object to keep track of unique values. Either approach will give you an array containing only unique objects based on a specified condition. Adjust the condition (item.id in the examples) according to your specific requirements.

Examples

  1. How to apply conditional filters to get unique values from a JSON array in JavaScript?

    • Description: This query seeks methods to filter out unique values from a JSON array based on specific conditions in JavaScript.
    const jsonArray = [{ id: 1, name: 'John' }, { id: 2, name: 'Jane' }, { id: 3, name: 'John' }]; const uniqueNames = Array.from(new Set(jsonArray.map(item => item.name)));

  2. JavaScript filter JSON array for unique values meeting specific criteria

    • Description: This query aims to filter a JSON array in JavaScript to obtain unique values based on certain conditions.
    const jsonArray = [{ id: 1, name: 'John' }, { id: 2, name: 'Jane' }, { id: 3, name: 'John' }]; const uniqueNames = jsonArray.filter((item, index, self) => self.findIndex(t => t.name === item.name && t.id === item.id) === index);

  3. How to remove duplicates from JSON array in JavaScript with conditions?

    • Description: This query focuses on eliminating duplicate entries from a JSON array in JavaScript while considering specific conditions.
    const jsonArray = [{ id: 1, name: 'John' }, { id: 2, name: 'Jane' }, { id: 3, name: 'John' }]; const uniqueNames = jsonArray.filter((item, index, self) => self.findIndex(t => t.name === item.name && t.id === item.id) === index);

  4. JavaScript: Filter unique objects from JSON array with a condition

    • Description: This query is about filtering unique objects from a JSON array in JavaScript, taking into account a specified condition.
    const jsonArray = [{ id: 1, name: 'John' }, { id: 2, name: 'Jane' }, { id: 3, name: 'John' }]; const uniqueNames = jsonArray.filter((item, index, self) => self.findIndex(t => t.name === item.name && t.id === item.id) === index);

  5. How to get distinct values from a JSON array in JavaScript with conditions?

    • Description: This query seeks ways to extract distinct values from a JSON array in JavaScript, considering specific conditions.
    const jsonArray = [{ id: 1, name: 'John' }, { id: 2, name: 'Jane' }, { id: 3, name: 'John' }]; const uniqueNames = Array.from(new Set(jsonArray.map(item => item.name)));

  6. JavaScript: Filtering unique values from JSON array based on condition

    • Description: This query pertains to filtering unique values from a JSON array in JavaScript while applying specific conditions.
    const jsonArray = [{ id: 1, name: 'John' }, { id: 2, name: 'Jane' }, { id: 3, name: 'John' }]; const uniqueNames = jsonArray.filter((item, index, self) => self.findIndex(t => t.name === item.name && t.id === item.id) === index);

  7. Removing duplicate objects from JSON array in JavaScript with conditions

    • Description: This query is about removing duplicate objects from a JSON array in JavaScript while considering specified conditions.
    const jsonArray = [{ id: 1, name: 'John' }, { id: 2, name: 'Jane' }, { id: 3, name: 'John' }]; const uniqueNames = jsonArray.filter((item, index, self) => self.findIndex(t => t.name === item.name && t.id === item.id) === index);

  8. JavaScript: Extracting unique values from JSON array with conditions

    • Description: This query looks for methods to extract unique values from a JSON array in JavaScript under specific conditions.
    const jsonArray = [{ id: 1, name: 'John' }, { id: 2, name: 'Jane' }, { id: 3, name: 'John' }]; const uniqueNames = Array.from(new Set(jsonArray.map(item => item.name)));

  9. How to filter out duplicates from JSON array in JavaScript based on specific criteria?

    • Description: This query aims to filter duplicate entries from a JSON array in JavaScript while considering particular criteria.
    const jsonArray = [{ id: 1, name: 'John' }, { id: 2, name: 'Jane' }, { id: 3, name: 'John' }]; const uniqueNames = jsonArray.filter((item, index, self) => self.findIndex(t => t.name === item.name && t.id === item.id) === index);

  10. Getting unique values from JSON array in JavaScript with conditions

    • Description: This query focuses on obtaining unique values from a JSON array in JavaScript, taking into account specific conditions.
    const jsonArray = [{ id: 1, name: 'John' }, { id: 2, name: 'Jane' }, { id: 3, name: 'John' }]; const uniqueNames = Array.from(new Set(jsonArray.map(item => item.name)));

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