A JavaScript FixedCache implementation

fixed-cache.js

/**
 * Creates a fixed-length cache
 *
 * @module FixedCache
 */
export default class FixedCache {
    /**
     * @param {Number} size Integer for the cache size
     */
    constructor(size) {
        if (size < 1) {
            throw new Error('Size cannot be smaller than one')
        }

        this.store = new Array(size).fill(null)
        this.ptr = 0
        this.size = size
    }

    /**
     * Set a cache item
     *
     * @param {string} key Resource identifier
     * @param {Object} value The value
     */
    set(key, value) {
        this.store[this.ptr] = {
            key,
            value
        }
        this.ptr = (this.ptr + 1) % this.size
    }

    /**
     * Get a value from the cache, or null
     *
     * @param {string} key The key of the value to search for
     * @returns {(Object|undefined)} The found (or not found) object
     */
    get(key) {
        return this.store.find((item) => item && item.key === key)
    }

    /**
     * Check if a key is currently in the cache
     *
     * @param {string} key The key of the value to search for
     * @returns {boolean} Wether the key was found in the cache
     */
    has(key) {
        return this.get(key) !== undefined
    }

    /**
     *
     * @param {string} key The key of the value to search for
     * @returns {Object|undefined} The popped value
     */
    pop(key) {
        const index = this.store.findIndex((item) => item && item.key === key)

        if (index === -1) {
            return
        }

        const item = this.store[index]
        this.store[index] = null
        return item
    }
}