js实现自加自减

 <input type="button" id="cut" name="jian" value="-" class="jian" onclick="cut()" />
<input type="button" name="count" value="1" class="changnum" /> 
<input type="button" id="add" name="jian" value="+" class="jian" onclick="add()" />

 

//添加商品数量
	function add() {
		var countValue = document.getElementById("count").value;
		var count = 0;
			count = parseInt(countValue) + 1;
			if (count == 10) {
				document.getElementById("add").setAttribute("disabled",
						"disabled");
			}
			if (count != 0) {
				document.getElementById("cut").removeAttribute("disabled");
			}
			document.getElementById("count").value = count;
	}
	//减少商品数量
	function cut() {
		var countValue = document.getElementById("count").value;
		var count = 0;
			count = parseInt(countValue) - 1;
			if (count == 0) {
				count = 1;
				document.getElementById("cut").setAttribute("disabled", "true");
			}
			if (count != 10) {
				document.getElementById("add").removeAttribute("disabled");
			}
			document.getElementById("count").value = count;
	}