var num = document.getElementById("num" + id)
var getNum = parseInt(num.value)
if(getNum > 1){
num.value = getNum - 1
}
}
function addNum(id){
var num = document.getElementById("num" + id)
num.value = parseInt(num.value) + 1
}
或者
var num = document.getElementById("num" + id)function subNum(id) {
var getNum = parseInt(num.value)
if(getNum > 1){
num.value = getNum - 1
}
}
function addNum(id){
num.value = parseInt(num.value) + 1
}
很简单啊，直接用字符串方法substring()截取最后一个数和最后第二个数就可以啊，你可以看下我这个代码符不符合你的要求：
<!DOCTYPE html><html>
<head>
<meta charset="UTF-8">
<title></title>
</head>
<body>
<script type="text/javascript">
var num = 123456789
function lastNumSum(num){
var str = num.toString()
var lastNum = str.substring(str.length-1,str.length)
var lastSecondNum = str.substring(str.length-2,str.length-1)
return Number(lastNum) + Number(lastSecondNum)
}
console.log(lastNumSum(num))
</script>
</body>
</html>
希望我的回答可以帮助到你！
可以用到js函数eval()，首先把数组转化为字符串，然后通过eval()函数计算字符串，得出结果。方法有很多种，举个例，var arr=['1','+','2','*','3']var b=arr.join('')var c=eval(b)输出c就能计算了.望采纳
