Javascript正则表达式应该允许空和非空字符串，但它不会

I've a regular expression that allows a string to be empty. If it isn't empty the string may contain only letters and spaces. But it may not start or end with a space.

我有一个正则表达式,允许字符串为空。如果它不为空,则字符串可能只包含字母和空格。但它可能无法以空间开始或结束。

This RegExp should do this job: ^(?! )[a-zA-Z]*[a-zA-Z ]*$ I've tested it here: http://tools.netshiftmedia.com/regexlibrary/

这个RegExp应该做这个工作:^(?!)[a-zA-Z] * [a-zA-Z] * $我在这里测试过:http://tools.netshiftmedia.com/regexlibrary/

But when I'm implementing this in my js, it doesn't allow a string to be empty.

但是当我在我的js中实现它时,它不允许字符串为空。

This is the code

这是代码

function validatePreposition(name) {
    string = string = document.forms['form'][name].value;
    pattern = new RegExp('^(?! )[a-zA-Z]*[a-zA-Z ]*$');

    checkString(name, pattern, string);
}

function checkString(name, pattern, string) {

    if(!pattern.test(string)) {
        error[name] = 1;
    } else {
        error[name] = 0;
    }

    printErrors();
}

How change my code so that an empty string is allowed?

如何更改我的代码以便允许空字符串?

2 个解决方案

#1

Try using this instead:

请尝试使用此代码:

pattern = /(^[a-zA-Z]+(\s*[a-zA-Z]+)*$)|(^$)/;

It will either test for an empty string or test for a string that starts with a a-Z and may have unlimited amount of spaces in the string but have to end with a-Z.

它将测试空字符串或测试以a-Z开头的字符串,并且可能在字符串中具有无限量的空格但必须以a-Z结尾。

You can see it in action here: http://jsfiddle.net/BAXya/

你可以在这里看到它:http://jsfiddle.net/BAXya/

2 个解决方案

#1

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