在Javascript中，如何检查字符串是否只是字母+数字（允许下划线）？

Question

How do I check that?

I want to allow all A-Za-z0-9 , and underscore. Any other symbol, the function should return false.

Answer 1

You can use a regular expression:

function isValid(str) { return /^\w+$/.test(str); }

\\w is a character class that represents exactly what you want: [A-Za-z0-9_] . If you want the empty string to return true , change the + to a * .

To help you remember it, the \\w is a w ord character. (It turns out that words have underscores in JavaScript land.)

Answer 2

I think this is a solution:

function check(input) {
  return /^\w+$/i.test(input);
}