How to Efficiently Remove Objects from an Array Based on Object Property in JavaScript?-JS Tutorial-php.cn

How to Efficiently Remove Objects from an Array Based on Object Property in JavaScript?

Linda Hamilton

Release： 2024-11-02 20:36:30

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How to Efficiently Remove Objects from an Array Based on Object Property in JavaScript?

Removing Objects from an Array Based on Object Property

In JavaScript, deleting an object from an array by matching a specific property can be challenging. This is because using the splice method, as commonly attempted, leads to a diminished array length as deletions occur.

Fix for Using Splice Method

To resolve this issue, you can implement a fix by decrementing the loop index when a deletion occurs:

<code class="javascript">for (var i = 0; i < arrayOfObjects.length; i++) {
    var obj = arrayOfObjects[i];

    if (listToDelete.indexOf(obj.id) !== -1) {
        arrayOfObjects.splice(i, 1);
        i--;
    }
}

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Overwriting Array Elements

Alternatively, you can avoid linear-time deletions by progressively overwriting the array elements you want to keep:

<code class="javascript">var end = 0;

for (var i = 0; i < arrayOfObjects.length; i++) {
    var obj = arrayOfObjects[i];

    if (listToDelete.indexOf(obj.id) === -1) {
        arrayOfObjects[end++] = obj;
    }
}

arrayOfObjects.length = end;

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Hash Set for Lookups

For efficient lookups, you can utilize a hash set:

<code class="javascript">const setToDelete = new Set(listToDelete);
let end = 0;

for (let i = 0; i < arrayOfObjects.length; i++) {
    const obj = arrayOfObjects[i];

    if (setToDelete.has(obj.id)) {
        arrayOfObjects[end++] = obj;
    }
}

arrayOfObjects.length = end;

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Helper Function

Encapsulate this approach into a helper function:

<code class="javascript">const filterInPlace = (array, predicate) => {
    let end = 0;

    for (let i = 0; i < array.length; i++) {
        const obj = array[i];

        if (predicate(obj)) {
            array[end++] = obj;
        }
    }

    array.length = end;
};</code>

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