如何使用正则表达式和JavaScript强制用户在输入字段中输入特定模式 [英] How do I force user to enter specific pattern in input field using regex and javascript

问题描述

我承认，尽管知道正则表达式的强大功能，但我从未对其进行过探索.并让我回味无穷. 我试图让用户在输入文本中输入模式P99999999，其中P是必需的，而99999999可以采用任何数字(不是字母).我正在触发键入，输入字段通过样式进行了大写，到目前为止，这是我所做的(我知道太少了).

I admit, I never explored into the regex albeit knowing its power. And its striking back to me. I am trying to make user enter pattern P99999999 into an input text where P is mandatory while 99999999 can take any digits(not letters). I'm triggering keyup, input field has uppercasing through styling and so far, this is what I have done (I know its too little).

inpt.value = $.trim( inpt.value );
if( inpt.value.indexOf( 'P' ) != 0 )
    inpt.value = inpt.value.replace(/[A-Z]/g, '');

经过一番探索，我想出了这个

After some exploring I come up with this

[P]+[0-9]+(?:\.[0-9]*)?

我不知道该如何验证我的输入.这是由在线工具生成的.我知道这不应该那么难.任何帮助.

I do not know how to validate my input against this. This was generated by an online tool. I know it shouldn't be that hard. Any help.

推荐答案

[已更新，以解决流输入(按住键)问题]

您去哪里

regex [它可能看起来像是非常规的，因为可能没有(*)数字，但是再想一想，它是实时验证，而不是最终结果验证]:

regex [ it might look unconventional as there can be none (*) digits but think again, it is a live validation not the final result validation ]:

^P\d*$

代码:

    $('input').on('change keyup keydown',function(){
        var txt = $(this).val();
        $(this).val(/^P\d*$/.test(txt)&txt.length<10?txt:txt.substring(0,txt.length-1));
    });

演示

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