如何强制用户只放数字

Question

我希望用户只能使用输入数字我已经尝试了几件事，比如oninput="this.value = this.value.replace(/[^0-9.]/g, '')和很多更多，但例如我发送的代码，如果我键入一个字母，并继续按键盘上的字母，它不会把它变成任何东西，我需要一个代码，将100％强制用户只键入数字无所谓如果我可以在用户不能删除的输入框中输入一个数字，例如0，那就好了。

Answer 1

您可以使用输入规范中提到的<input type=...> 。

Answer 2

There are a few different ways to accomplish this but one of them would be capturing the keypress itself and returning false if the input is not a number.

Also if I understand you correctly, to add a default value of "0", just define it in the input directly like value="0" , or you could use a placeholder="0" if that's what you're looking for.

 <input type="number" value="0" onkeydown="javascript: return event.keyCode === 8 || event.keyCode === 46 ? true : !isNaN(Number(event.key))" /> 

Answer 3

While this wouldn't enforce the user input to numbers only, you may want to consider using the pattern attribute to leverage some built-in behaviour. If you type non-numeric characters, the text colour will turn red:

 input:invalid { color: red; } 

 <input type="text" pattern="[0-9]+"/> 

Then we can start looking at the constraint validation API :

The Constraint Validation API enables checking values that users have entered into form controls, before submitting the values to the server.

If you type non-numeric characters and try to submit the form, you should see a built-in tooltip displaying a custom error message:

 const input = document.querySelector('input'); input.addEventListener('invalid', () => { if (input.validity.patternMismatch) { input.setCustomValidity('Numbers only please!!'); } }); 

 input:invalid { color: red; } 

 <form> <input type="text" pattern="[0-9]+"/> <button type="submit">submit</button> </form> 

Answer 4

  $("#but").click(function(){ let inp_val = $("#txt").val(); if(isNaN(inp_val)){ alert("Just enter a number."); $("#txt").val(""); } }) 

 <script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script> <input type="text" id="txt"> <input type="button" value="CLICK" id="but">