[Manyahin]

var $ = (function(){
	function jQuery() {
		this.elms = null;
		return this;
	}
	jQuery.prototype.query = function(query) {
		this.elms = document.querySelectorAll(query);
		return this;
	}
	jQuery.prototype.text = function(str){
		if(!this.elms) return this;
		Array.prototype.forEach.call(this.elms, function(elm){
			elm.textContent = str;
		});
		console.log(this);
		return this;
	}
	return function(query){
		var $ = new jQuery;
		return $.query(query);
	};
})();

$('.a').text('X');

second

var $ = (function(){
	var elms = null, self = {
		text: function(str){
			if(!elms) return this;
			Array.prototype.forEach.call(elms, function(elm){
				elm.textContent = str;
			});
			return this;
		}
	}; 
	return function(query){
		elms = document.querySelectorAll(query);
		return self;
	};
})();

тут chain можно сделать

$('.a').text('t').text('z')

nvm, thx