我正在创建的计算器表单上进行验证，如果用户没有在输入中输入数字，我想显示一条"请填写此字段"消息。

默认情况下，字段中有一个"0"。

因此，我要检查字段是否为空或是否具有字符串"0"。

还应该提到有一个脚本正在运行，它阻止用户输入非数字字符。

这是一系列签入if/else语句的一部分。对于这种情况，我已经有一个条件(选择用户以前的选择)。

所以我有点像：

我想精简一下。我真正想要的是：

有什么想法吗？

我看过以下相关问题，但还没能从他们的答案中找出答案：

如何检查javascript中的空字符串？

javascript：检查变量是否等于两个或多个值的简单方法？

---

字母名称

---

(P)你可以写(p)(P)字母名称(p)(P)如果这个方法对我好但对我有用(p)

---

(P)为了记录，这个Regex测试也有效。It's testing for an empty string or the string'0:(p)字母名称(P)I had tried this before but there must have been a problem elsewhere in my code.Now it works.(cheers to nils in the comments to the question for pointing out that this works).(p)

---

(P)Thanks for answering everyone.真的很好的解决办法Seems so obvious now to have a'0'placeholder and only test for empty.Also Akmed0zmey's solution is talius.(p)(P)I forgot to mention that there is no need to trim as I have a script running that prevents the users from putting in non-numeric characters，including spaces.I have updated the original question to include this.(p)(P)I went with rich's solution a s it most closely answers the specific problem I asked and it's a good method to retain for the future-I could have a series of strings to test against.(p)(P)Thanks！(p)

---

(P)A solution could be based on the following.(p)字母名称(P)As an Aside，note that instead of having a default value of"0"in your inputs you could set the EDOCX1 nipal 0 attribute of the input to 0.(p)字母名称(P)That way you don't need to check if the input is"0"，and you could actually treat"0"as a valid input if desired.(p)

---

(P)If(Calchoice=-1&；&Amp；($…)，35；Input-loan；()，val()=124；&124；("，35；input-loan")；val(="0").//do some；注(p)(P)试着在这里保持神秘。Similarly，you can also use$ISMPtyobject(object)to ensure whether the value is empty or not.(p)

---