@ckeditor/ckeditor5-utils/src/splicearray.js

Miscellaneous utilities used by CKEditor 5.

/**
 * @license Copyright (c) 2003-2025, CKSource Holding sp. z o.o. All rights reserved.
 * For licensing, see LICENSE.md or https://ckeditor.com/legal/ckeditor-licensing-options
 */
/**
 * @module utils/splicearray
 */
/**
 * Splices one array into another. To be used instead of `Array.prototype.splice` for better
 * performance and because the latter may throw "Maximum call stack size exceeded" error when
 * passing huge number of items to insert.
 *
 * ```ts
 * spliceArray( [ 1, 2 ], [ 3, 4 ], 0 );	// [ 3, 4, 1, 2 ]
 * spliceArray( [ 1, 2 ], [ 3, 4 ], 1 );	// [ 1, 3, 4, 2 ]
 * spliceArray( [ 1, 2 ], [ 3, 4 ], 2 );	// [ 1, 2, 3, 4 ]
 * spliceArray( [ 1, 2 ], [],       0 );	// [ 1, 2 ]
 * ```
 *
 * @param targetArray Array to be spliced.
 * @param insertArray Array of elements to be inserted to target.
 * @param index Index at which nodes should be inserted.
 *
 * @returns New spliced array.
 */
export default function spliceArray(targetArray, insertArray, index) {
    const originalLength = targetArray.length;
    const insertLength = insertArray.length;
    // Shift elements in the target array to make space for insertArray
    for (let i = originalLength - 1; i >= index; i--) {
        targetArray[i + insertLength] = targetArray[i];
    }
    // Copy elements from insertArray into the target array
    for (let i = 0; i < insertLength; i++) {
        targetArray[index + i] = insertArray[i];
    }
}