I have tried to implement that the combinations are not repeated. in the image you can see how "sd" is repeated twice.

sd

const characters ='qwertyuiopasdfghjklzxcvbnm0987654321';

function generateString(length) {
    let result = ' ';
    const charactersLength = characters.length;
    for ( let i = 0; i < length; i   ) {
        result  = characters.charAt(Math.floor(Math.random() * charactersLength));
    }

    return result;
}



function captura(){
    lon=2;
    can=600;
    for (let i = 0; i < can; i  ) {
        document.write(i 1   ".- "   generateString(lon)   "<br>");
    }

}
captura();

Any help please?

CodePudding user response：

Just save the results in a Set and make sure that what you return at the end isn't in the Set already.

const characters ='qwertyuiopasdfghjklzxcvbnm0987654321';

function generateString(length) {
    let result = ' ';
    const charactersLength = characters.length;
    for ( let i = 0; i < length; i   ) {
        result  = characters.charAt(Math.floor(Math.random() * charactersLength));
    }

    return result;
}
const set = new Set();
const generateUniqueString = (len) => {
  let str;
  do {
    str = generateString(len);
  } while (set.has(str));
  set.add(str);
  return str;
};


function captura(){
    for (let i = 0; i < 50; i  ) {
        document.write(i 1   ".- "   generateUniqueString(2)   '<br>');
    }

}
captura();

If you use this in a situation where you'll start getting anywhere near the limit of uniques, a better approach would be to generate all possible combinations in advance, randomize the array, then continually pop strings from the array when the function is called.

CodePudding user response：

Given your script one approach would be to loop through the results, and get rid of b where a === b.

Then generate new random strings to fill the difference up until you get no new equivalence.