Question

我需要验证字符串只包含字母，数字最多为4，＆＃39;。＆＃39;和＆＃39; _＆＃39;;

现在我正在使用

if(/^[a-zA-Z0-9_.]+$/.test(testString)) 
{
     console.log("Valid string");
}

testString = test.com // (must be valid) 
testString = Te_St.com // (must be valid) 
testString = Te_St1.com // (must be valid) 
testString = Te_St12.com // (must be invalid because has 12 in it and is higher than 4) 
testString = Te_2St1.com // (must be valid) 
testString = Te_24St1.com // (must be invalid because has 24 in it and it higher than 4) 
testString = Te_2$St1.com // (must be invalid because has ilegal character $)

Answer 1

您可以尝试以下模式：

/^[a-z._]*(?:[01234](?:[a-z._]+|$))*$/i

但请注意，此模式使用空字符串成功。为了防止这种情况，您可以在模式开始之前测试字符串长度或添加前瞻：

/^(?=.)[a-z._]*(?:[01234](?:[a-z._]+|$))*$/i

Answer 2

^(?!.*[1-9]\d)[a-zA-Z0-4_.]+$

试试这个。看看演示。

https://regex101.com/r/wU7sQ0/12

Reg表达式javascript

2 个答案: