javascript 积极和消极的前瞻

Posted 2021-05-03

let quit = "qu";
let noquit = "qt";

let quRegex = /q(?=u)/;
let qRegex = /q(?!u)/;

quit.match(quRegex);    // returns ["q"]
noquit.match(qRegex);     // returns ["q"]


// check for two or more patterns in one string
// the below looks for between 3 and 6 characters and at least 1 number
let password = "abc123";
let checkPass = /(?=\w{3,6})(?=\D*\d)/;
checkPass.test(password);   // returns true