Use JavaScript's Array.filter method to efficiently filter out duplicates without causing any UI slowdown

Question

Use JavaScript's Array.filter method to efficiently filter out duplicates without causing any UI slowdown

In a unique case I'm dealing with, certain validation logic needs to occur in the UI for specific business reasons[...]. The array could potentially contain anywhere from several tens to hundreds of thousands of items (1-400K). This frontend operation is Angular-based.

One of the initial steps involves checking for duplicates within the array and storing them separately[...]. To achieve this, the following code snippet is used:

validateTargets(targets: string[]): ValidationResultObject[] {

    let result: ValidationResultObject[];
    let dups: string[] = [];

    var uniques = targets.filter( (item,index) => {
        if (targets.indexOf(item) === index) {
            return targets.indexOf(item) === index
        }
        else {
            dups.push(targets[index])
        }
    }

    //additional validation procedures are carried out here

    return result;
}

The main issue arises when processing an array above 50K items, causing a noticeable freeze in the UI. As a temporary fix, the aforementioned callback function has been placed within a setTimeout, allowing a spinner to indicate activity while the page hangs :)

Various suggestions exist on how to structure code to ensure UI responsiveness, but my scenario presents a challenge due to duplicate handling.

One potential solution considered was breaking down the array into chunks and processing the Array.filter method in a loop using setTimeout for UI responsiveness. However, eventually comparing these chunks against each other would only prolong the process! With some browser limitations within the organization, experimenting with workers isn't currently feasible.

If anyone has insight or suggestions on how to address this dilemma, it would be greatly appreciated. Unfortunately, migrating this functionality to the backend is not an option :(

Best Regards

javascript typescript loops browser array-filter

Answer 1

Answer №1

If you want to efficiently filter out duplicate elements from an array, consider using the following code:

let uniqueItems = targets.reduce((result, item) => {
  result[item] = 1;
  return result;
}, {});
let noDuplicates = Object.keys(uniqueItems);

This method only requires one pass over the array and takes advantage of the internal efficiency of property name lookup for faster processing compared to using .indexOf() for sequential search. When dealing with arrays containing a large number of elements, this approach should significantly reduce execution time.

Answer 2

If you want to efficiently filter out duplicate elements from an array, consider using the following code:

let uniqueItems = targets.reduce((result, item) => {
  result[item] = 1;
  return result;
}, {});
let noDuplicates = Object.keys(uniqueItems);

This method only requires one pass over the array and takes advantage of the internal efficiency of property name lookup for faster processing compared to using .indexOf() for sequential search. When dealing with arrays containing a large number of elements, this approach should significantly reduce execution time.

Answer 3

Answer №2

To efficiently process a large amount of data, consider implementing an asynchronous function. Once the processing is complete, use a callback to pass the result as an argument and resume normal flow.

async validateTargets(targets: string[], callback: function): {
 //...Custom logic
 callback(result)
}

If you need to eliminate duplicates, you can utilize

[...new Set(items)]

Important: The above approach assumes that the Items array only contains primitive values.

Answer 4

To efficiently process a large amount of data, consider implementing an asynchronous function. Once the processing is complete, use a callback to pass the result as an argument and resume normal flow.

async validateTargets(targets: string[], callback: function): {
 //...Custom logic
 callback(result)
}

If you need to eliminate duplicates, you can utilize

[...new Set(items)]

Important: The above approach assumes that the Items array only contains primitive values.

Answer 5

Answer №3

Although I have not encountered this scenario before, my advice would be to consider utilizing the Set type in JavaScript. This data structure automatically removes duplicates internally, making it more efficient than using filter methods. For reference, you can read more about the performance comparison between JS Set vs Array. In case there are browsers that do not support Set, you can always use a polyfill as an alternative solution.

Answer 6

Although I have not encountered this scenario before, my advice would be to consider utilizing the Set type in JavaScript. This data structure automatically removes duplicates internally, making it more efficient than using filter methods. For reference, you can read more about the performance comparison between JS Set vs Array. In case there are browsers that do not support Set, you can always use a polyfill as an alternative solution.

Use JavaScript's Array.filter method to efficiently filter out duplicates without causing any UI slowdown

Answer №1

Answer №2

Answer №3

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