javascript 只允许小写字符
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Allow only lowercase characters
提问by Vpp Man
I use following code to check if a user input is lowercase or not. I will allow characters from ato z. no other characters allowed.
我使用以下代码来检查用户输入是否为小写。我将允许字符从a到z。不允许使用其他字符。
JavaScript file:
JavaScript 文件：
var pat = /[a-z]/;
function checkname()
{
var t = $("input[name='user_name']").val();
if(pat.test(t) == false)
{
alert('Only lowercase characters allowed');
}
}
//... other functions
But this donot work all the time. If I enter industrialS, it will not find that capital 'S'.
但这并不总是有效。如果我输入industrialS，它不会找到大写的“S”。
I also tried: /^[a-z]$/and /[a-z]+/. But not working.
我也试过：/^[a-z]$/和/[a-z]+/。但不工作。
PLease help me.
请帮我。
回答by Pointy
Your regular expression just checks to see if the string has anylower-case characters. Try this:
您的正则表达式只是检查字符串是否有任何小写字符。试试这个：
var pat = /^[a-z]+$/;
That pattern will only match strings that have one or more lower-case alphabetic characters, and no other characters. The "^" at the beginning and the "$" at the end are anchors that match the beginning and end of the tested string.
该模式将仅匹配具有一个或多个小写字母字符的字符串，而不会匹配其他字符。开头的“^”和结尾的“$”是匹配测试字符串开头和结尾的锚点。
回答by Ananta Prasad
if((/[a-z]/.test(email))==true){//allow the small characters}回答by 0lukasz0
Your regexp should be:
你的正则表达式应该是：
/^[a-z]+$/
回答by jacob
Since all you want is lower case letters, instead of just telling the user s/he's done something wrong, I would fix it:
由于您想要的只是小写字母，而不是仅仅告诉用户他/她做错了什么，我会修复它：
function checkname() {
var disallowed = /[^a-z]/gi; // g=global , i=case-insensitive
if (this.value == disallowed) {
//delete disallowed characters
this.value = this.value.replace(disallowed,'');
alert('Only lowercase letters allowed');
//instead of an alert, i would use a less intrusive fadeIn() message
}
this.value = this.value.toLowerCase();
}
