<input id="amountInput" onfocus="Num(this)" onkeyup="Num(this)" onafterpaste="Num(this)"
maxlength="10" class="form-control" placeholder="请输入认证购买金额"/> 元
function Num(obj) {
var integer;
var decimal;
if (obj.value != "") {
obj.value = obj.value.replace(/[^\d.]/g, "");
obj.value = obj.value.replace(/^\./g, "");
obj.value = obj.value.replace(/\.{2,}/g, ".");
obj.value = obj.value.replace(".", "$#$").replace(/\./g, "").replace("$#$", ".");
obj.value = obj.value.replace(/^(\-)*(\d+)\.(\d\d).*$/, '$1$2.$3');
if (obj.value.indexOf(".") > -1) {
integer = obj.value.split(".")[0];
decimal = obj.value.split(".")[1];
obj.value = Math.round(integer) + "." + decimal;
} else {
obj.value = Math.round(obj.value);
}
}
}