(function() {
	var but = [];
	var br = [];
	var br1 = [];
	var img = document.images[0];
	var arr = ["img/2.png", "img/3.png", "img/4.png", "img/5.png"]
		for (var i = 0, j = 1; i < arr.length; i++, j++) {
			 but[i] = document.createElement("button");
				br[i] = document.createElement("br");
				br1[i] = document.createElement("br");
				but[i].value = arr[i];
				but[i].innerHTML = "Click " + j;
		document.body.appendChild(but[i]);
		document.body.appendChild(br[i]);
		document.body.appendChild(br1[i]);


		}
	var but = document.getElementsByTagName("button");

	 for (var i = 0; i < but.length; i++) {
	 	but[i].addEventListener("click" , function() {
	 		img.src = this.value;
	 	})
	}

}());

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<img src="img/1.png" alt="one"><br>