问题
\w - stands for [A-Za-z0-9_] Character class
But i am not able to understand how it is interpreted inside character class.
So when i use
[\w-~]
let test = (str) => /^[\w-~]+$/.test(str)
console.log(test("T|"))it fails for T|
but when i am using
[A-Za-z0-9_-~]
let test = (str) => /^[A-Za-z0-9_-~]+$/.test(str)
console.log(test("T|"))it results in true,
i am not able to understand how these two expressions are different from each other ?
回答1:
I believe that the main difference between both your examples is the location of your - character. What's happening here is that in this example:
let test = (str) => /^[A-Za-z0-9_-~]+$/.test(str)
console.log(test("T|"))
It's evaluated as a range, like so:
let test = (str) => /^[_-~]+$/.test(str)
console.log(test("|"))
will return true.
Where in this one:
let test = (str) => /^[\w-~]+$/.test(str)
console.log(test("T|"))
Since \w is a set of characters in and of itself, it's evaluating the character - by itself.
The position of - and it's surrounding can make a huge difference in how it's interpreted.
You could avoid that situation, altogether, by moving it to the end, like so:
let test = (str) => /^[A-Za-z0-9_~-]+$/.test(str)
console.log(test("T|"))
which will return false
回答2:
I guess range is doing everything here, when you use ^[A-Za-z0-9_-~]+$
_-~ matches a single character in the range between _ (index 95) and ~ (index 126) (case sensitive) that's why T| get matched and returns true but when you use ^[\w-~]+$ it is not forming any range of characters like _-~ to match so it fails and returns false
See ^[A-Za-z0-9-~]+$ also returns false because it doesn't include the _ character to make the range _-~ between _ (index 95) and ~ (index 126)
let test = (str) => /^[A-Za-z0-9-~]+$/.test(str)
console.log(test("T|"))See https://regex101.com/r/vbLN9L/5 here on the EXPLANATION section.
来源：https://stackoverflow.com/questions/56572373/how-word-character-is-interpreted-in-character-class