问题
I'm looking for an efficient way to build a random string that has specific requirements but can vary in length. It must:
- Contain at least one uppercase character.
- Contain at least one lowercase character.
- Contain at least one number.
- Contain at least one of the special characters: _-|@.,?/!~#$%^&*(){}[]+=
The random string doesn't have to be unique but if it is, its better. It will be used in a node.js server so any crypto library can be made use of. I saw Math.random().toString(36) which comes close but doesn't get me everything. I'm not sure if I should just try to build a regex for this.
回答1:
var randomString = (function() {
// Define character classes to pick from randomly.
var uppers = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ';
var lowers = 'abcdefghijklmnopqrstuvwxyz';
var numbers = '0123456789';
var specials = '_-|@.,?/!~#$%^&*(){}[]+=';
var charClasses = [uppers, lowers, numbers, specials];
var minLen = charClasses.length;
function chooseRandom(x) {
var i = Math.floor(Math.random() * x.length);
return (typeof(x)==='string') ? x.substr(i,1) : x[i];
}
// Define the function to actually generate a random string.
return function(maxLen) {
maxLen = (maxLen || 36);
if (maxLen < minLen) { throw new Error('length must be >= ' + minLen); }
do { // Append a random char from a random char class.
var str='', usedClasses={}, charClass;
while (str.length < maxLen) {
charClass = chooseRandom(charClasses);
usedClasses[charClass] = true;
str += chooseRandom(charClass);
}
// Ensure we have picked from every char class.
} while (Object.keys(usedClasses).length !== charClasses.length);
return str;
}
})();
randomString(); // => "o4m3H@YC7j0r@^gsY@1vlg2]cI66|9^beZ1)"
randomString(); // => "R6-K0Kq%4O0Je*=iPbVaV|bo-_,,g[j8wTW2"
randomString(); // => "!uu5NUWs1P}SRN78l}32Gno$]2m5PV+h+wTG"
回答2:
Regex are used to check, capture, split or replace something in a string, you can't build something from zero with them.
However you can make some replacement in a string that contain a random generated number to have that you want.
来源：https://stackoverflow.com/questions/17088798/javascript-node-js-specific-random-string-builder