仅使用charectors对字母数字开始的Javascript验证,允许所有特殊的charectors但不允许启动空格 [英] Javascript validation for alphanumeric start with only charectors, allow all special charectors but not allow starting white space
问题描述
仅使用charectors的字母数字开始的Javascript验证,允许所有特殊的charectors但不允许启动空格。考试:
(考试12) - 允许
(test12) - 允许
(测试) - 允许
(12) - 允许
(test12) - 不允许(不允许以空格开头)
(test12 $%^#@ ) - 允许等..
%^#@) - 允许等..
使用正则表达式,正则表达式适合你的目的是:
^ [a-zA-Z0-9] \。?
^ [ a-zA-Z]的意思是从任何字母数字小或首都开始
\。是指'包括数字和特殊字符在内的任何字符'
?表示零或更多
了解有关 Regex 和在javascript中使用它的示例 [ ^ ]。
请尝试下面的示例代码:< br $> b $ b
< script >
function validate(){
var regex = / ^ [a-zA-Z0-9] \。 ?/ //正则表达式
if(document.myform.myinput.value.search(regex)== - 1)
{//如果匹配失败
alert(请输入有效输入。)
} else {//如果匹配传递
alert(谢谢你。)
}
}
< / script >
< form name = myform >
< 输入 type = text 名称 = myinput size = 15 >
< 输入 type= 按钮 onClick = validate() value = check >
< / form >
>
我在pettern下方使用,这将满足我的要求。
var patren = / ^ [a-z0-9] + [a-z0-9] \。?/ ;
Javascript validation for alphanumeric start with only charectors, allow all special charectors but not allow starting white space. Exam:
(test 12) - allow
(test12) - allow
(test) - allow
(12) - allow
( test12) - not allow (starting with white space not allowed)
(test12$%^#@) - allow etc..
%^#@) - allow etc..
Use Regex, the regex that fits your purpose is:
^[a-zA-Z0-9]\.?
^[a-zA-Z] means 'start with any alphanumeric small or capital'
\. means 'any character including number and special characters'
? means 'zero or more'
Learn more about Regex and an Example to use it in javascript[^].
Try my sample code below:
<script> function validate(){ var regex=/^[a-zA-Z0-9]\.?/ //regular expression if (document.myform.myinput.value.search(regex)==-1) { //if match failed alert("Please enter a valid input.") } else { // if match passed alert("Thank you.") } } </script> <form name="myform"> <input type="text" name="myinput" size=15> <input type="button" onClick="validate()" value="check"> </form>
Hi,
I am using below pettern and this will fulfill my requirement.
var patren=/^[a-z0-9]+[ a-z0-9]\.?/;
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