jQuery 当长度为0时，如何防止用户在文本框中输入特殊字符？
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How to prevent user from entering special characters in text box when length is 0?
提问by Bittu
I have the following code which prevents user from entering space when the length is 0. Now, how can I prevent user from entering all special characters(anything other than a-z A-Z 0-9) when the length is 0?
我有以下代码可以防止用户在长度为 0 时输入空格。现在，当长度为 0 时，如何防止用户输入所有特殊字符（az AZ 0-9 以外的任何字符）？
$('#DivisionName').bind('keypress', function(e) {
if($('#DivisionName').val().length == 0){
if (e.which == 32){//space bar
e.preventDefault();
}
}
});
This is my text box.
这是我的文本框。
<input type="text" id="DivisionName" />
回答by Ja?ck
The letter and digit ranges are (inclusive):
字母和数字范围是（包括）：
- 97 - 122 (a-z)
- 65 - 90 (A-Z)
- 48 - 57 (0-9)
- 97 - 122 (az)
- 65 - 90 (AZ)
- 48 - 57 (0-9)
This is what you compare e.whichagainst.
这就是你比较的e.which对象。
if (e.which < 48 ||
(e.which > 57 && e.which < 65) ||
(e.which > 90 && e.which < 97) ||
e.which > 122) {
e.preventDefault();
}
Or, using inverse logic:
或者，使用逆逻辑：
var valid = (e.which >= 48 && e.which <= 57) || (e.which >= 65 && e.which <= 90) || (e.which >= 97 && e.which <= 122);
if (!valid) {
e.preventDefault();
}
Update
更新
Even so, you may still wish to validate the field contents as a whole using a regular expression:
即便如此，您可能仍然希望使用正则表达式来验证整个字段内容：
if (/^[A-Z0-9]+$/i.test(value)) {
// it looks okay now
}
Or fix the field by replacing the bad stuff:
或者通过替换坏的东西来修复该字段：
var stripped = value.replace(/[^A-Z0-9]+/i, '');
回答by Scheintod
This is what you are looking for:
这就是你要找的：
$('#DivisionName').bind('keypress', function(e) {
if($('#DivisionName').val().length == 0){
var k = e.which;
var ok = k >= 65 && k <= 90 || // A-Z
k >= 97 && k <= 122 || // a-z
k >= 48 && k <= 57; // 0-9
if (!ok){
e.preventDefault();
}
}
});
or see here: http://jsfiddle.net/D4dcg/
或在这里查看：http: //jsfiddle.net/D4dcg/
回答by Boranas
You can use a regex to validate the string.
Something like ^[a-zA-z0-9].*
您可以使用正则表达式来验证字符串。就像是^[a-zA-z0-9].*
Here is an article about testing a regex in javascript : http://www.w3schools.com/jsref/jsref_regexp_test.asp
这是一篇关于在 javascript 中测试正则表达式的文章：http: //www.w3schools.com/jsref/jsref_regexp_test.asp
And you can even bind a change event and not a keypress.
您甚至可以绑定更改事件而不是按键。
