javascript 检查按键上的正则表达式
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Checking regex expression on keypress
提问by Adam Mrozek
I would like to create my own plugin (without use any external libraries - it's for learning purpose) to validate text typed by user dynamically in regex test function.
我想创建自己的插件（不使用任何外部库 - 用于学习目的）来验证用户在正则表达式测试函数中动态输入的文本。
In example I have regex pattern:
例如，我有正则表达式模式：
^.{2}$
^.{2}$
And javascript function
和 javascript 函数
$('#textbox').bind("keypress", function (event) {
var key = String.fromCharCode(!event.charCode ? event.which : event.charCode);
if (!regex.test(key)) {
event.preventDefault();
return false;
}
});
Now, I want to type two dots into textbox, but after first keypress is fired, one dot doesn't match to the pattern and nothing happens because event is prevented.
现在，我想在文本框中输入两个点，但是在触发第一次按键后，一个点与模式不匹配，并且没有任何反应，因为事件被阻止。
My question: Is it possible to check if currently typed text matches with regex pattern?
我的问题：是否可以检查当前输入的文本是否与正则表达式匹配？
回答by Fest7
Your regex only accept two dots (..), but you're testing a single character!
您的正则表达式只接受两个点 (..)，但您正在测试单个字符！
var regex = new RegExp("^.{2}$");
$('#textbox').bind("keypress", function (event) {
var key = String.fromCharCode(!event.charCode ? event.which : event.charCode);
if (!regex.test(key)) {
event.preventDefault();
return false;
}
});
Wanna check current typed text when users finished typing? .. Look HERE
想在用户完成输入时检查当前输入的文本吗？..看这里
回答by Akshay
You can try keydown as it will trigger as soon as you press a key and before character is displayed in textbox. So if it doesnot match with the pattern you can return out.
您可以尝试使用 keydown，因为它会在您按下一个键并在文本框中显示字符之前立即触发。因此，如果它与模式不匹配，您可以返回。
回答by onerror
$('#textbox').bind("keyup", function (event) {
var user_input = getElementById ("your_input_id_here");
if (!regex.test(user_input)) {
return false;
}
});
So, essentially you should use onkeyup instead and you should check the whole user input, not just the last key
因此，本质上您应该改用 onkeyup 并且您应该检查整个用户输入，而不仅仅是最后一个键
回答by Tamilselvan K
var alpha = /[ A-Za-z]/;
var numeric = /[0-9]/;
var alphanumeric = /[ A-Za-z0-9]/;
function validateKeypress(validChars) {
var keyChar = String.fromCharCode(event.which || event.keyCode);
return validChars.test(keyChar) ? keyChar : false;
}
The HTML will have to change to onkeypress="validateKeypress(alpha);"
HTML 必须更改为 onkeypress="validateKeypress(alpha);"
回答by Harshad Khandagale
var in_put = document.getElementById("in_put"),
key = null;
in_put.addEventListener("keydown", match_input);
function match_input(e){
console.log("Key: "+e.key);
key = e.key;
console.log("Match: "+key.match(/a/i));//return array of match
if(key.match(/a/i)){
//code on succession.
}else{
//code on failure.
}
}
Note: Change /a/i with your /pattern/ig. It only check for input is a/A.
注意：将 /a/i 更改为您的 /pattern/ig。它只检查输入是 a/A。
