How to Efficiently Filter Array Objects by Property Value in JavaScript?-JS Tutorial-php.cn

How to Efficiently Filter Array Objects by Property Value in JavaScript?

Barbara Streisand

Release： 2024-10-29 14:45:02

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How to Efficiently Filter Array Objects by Property Value in JavaScript?

Filtering Array Objects by Property Value

To efficiently remove objects from an array based on a specific property, consider the following solutions:

1. In-Place Filtering:

To decrement the array length correctly, implement decrementing i after removing an item:

<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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2. Overwriting Elements:

Overwrite elements you want to keep to avoid linear-time deletions:

<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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3. Hash Set Optimization:

For modern runtimes, use a hash set to speed up lookups:

<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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4. Reusable Function (Optional):

Wrap the filtering operation in a reusable 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;
};

const toDelete = new Set(['abc', 'efg']);

const arrayOfObjects = [{id: 'abc', name: 'oh'},
                        {id: 'efg', name: 'em'},
                        {id: 'hij', name: 'ge'}];

filterInPlace(arrayOfObjects, obj => !toDelete.has(obj.id));
console.log(arrayOfObjects); // [{id: 'hij', name: 'ge'}]</code>

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These solutions efficiently filter and remove objects from the array based on their specified property values.

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