<head>
<script>
function check(text1){
var exp=/^(-1\+)?\d+(\.\d+)?$/;
var x=exp.test(text1);
if(!x){alert("请输入正、负数或小数!");}}
</script></head>
<body><input type=text onchange="check(this.value)"></body>
<script>
function check(text1){
var exp=/^(-1\+)?\d+(\.\d+)?$/;
var x=exp.test(text1);
if(!x){alert("请输入正、负数或小数!");}}
</script></head>
<body><input type=text onchange="check(this.value)"></body>
var exp=/^(-1\+)?\d+(\.\d+)?$/;===》
var exp=/^(\-|\+)?\d+(\.\d+)?$/;