typewriter.js

(function(){

this.Terminal = function(container, steps){
    this.container = document.getElementById(container);
    this.steps = steps;
    this.cycle = this.cycle.bind(this);
    this.cycle();
};

this.Terminal.prototype.cycle = function(){
    if (!this.current) {
        if (!this.steps.length) {
            return;
        }
        this.current = this.steps.shift();
        if (this.current.display === 'typewriter') {
            this.current.text = this.current.text.split('');
        }
        if (this.current.delay) {
            clearTimeout(this._timer);
            this._timer = setTimeout(this.cycle, this.current.delay);
            return;
        }
    }

    if (this.current.display === 'typewriter') {
        if (!this.current.element) {
            this.current.element = document.createElement('div');
            this.container.appendChild(this.current.element);
            this.current.element.innerHTML = this.current.prefix || '';
        }

        this.current.element.innerHTML += this.current.text.shift();

        if (!this.current.text.length) {
            this.current = null;
            return this.cycle();
        } else {
            clearTimeout(this._timer);
            this._timer = setTimeout(this.cycle, 40);
            return;
        }
    }

    if (this.current.display === 'instant') {
        this.current.element = document.createElement('div');
        this.current.element.innerHTML = this.current.text;
        this.container.appendChild(this.current.element);
        this.current = null;
        return this.cycle();
    }
};

}).call(this);