<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>lik-input-number</title>
</head>
<body>
<input type="text" class="lik_input_number" style="color:#ccc" value="请输入数字" onfocus="fn_focus(this);" onblur="fn_blur(this);" onkeydown="value = this.value.replace(/[^0-9.]/g, '');" onkeyup="value = this.value.replace(/[^0-9.]/g, '');">
</body>
<script src="jquery-1.8.1.min.js"></script>
<script>
// 输入框模拟placeholder
function fn_focus(ele) {
if (ele.value == ele.defaultValue) {
ele.style = "color:#333";
ele.value = '';
} else {
ele.style = "color:#333";
}
}
function fn_blur(ele) {
var reg = /^[s]*$/;
if (reg.test(ele.value) || ele.value == ele.defaultValue) {
ele.style = "color:#ccc";
ele.value = ele.defaultValue;
} else {
ele.style = "color:#333";
}
}
</script>
</html>