queue-vanilla.js

(function exposeQueue(root){
    function validateTasks(tasks){
        const invalidIndex=tasks.findIndex(task=>typeof task !== 'function');
        if(invalidIndex !== -1){
            throw new TypeError(`Queue task at index ${invalidIndex} must be a function.`);
        }
    }

    class Queue{
        #contents=[];
        #running=false;

        constructor(){
            this.autoRun=true;
            this.stop=false;
        }

        add(...tasks){
            validateTasks(tasks);
            this.#contents.push(...tasks);

            if(!this.#running && !this.stop && this.autoRun){
                this.next();
            }

            return this;
        }

        next(){
            if(this.stop || this.#contents.length === 0){
                this.#running=false;
                return;
            }

            this.#running=true;
            const task=this.#contents.shift();

            try{
                task.call(this);
            }catch(error){
                this.#running=false;
                throw error;
            }
        }

        clear(){
            this.#contents=[];
            return this.#contents;
        }

        get contents(){
            return this.#contents;
        }

        set contents(tasks){
            if(!Array.isArray(tasks)){
                throw new TypeError('Queue contents must be an array of functions.');
            }

            validateTasks(tasks);
            this.#contents=tasks;
        }

        get running(){
            return this.#running;
        }

        get size(){
            return this.#contents.length;
        }
    }

    Object.defineProperty(root,'Queue',{
        configurable:true,
        enumerable:true,
        value:Queue,
        writable:true
    });
})(globalThis);