list-of-unique-ids.js

let ids = [];

const fs = require('fs');

if(!String.prototype.padStart) {
    String.prototype.padStart = function padStart(targetLength, padString) {
        targetLength = targetLength >> 0;
        padString = String(padString || ' ');
        if(this.length > targetLength) {
            return String(this);
        }
        else {
            targetLength = targetLength - this.length;
            if(targetLength > padString.length) {
                padString += padString.repeat(targetLength / padString.length);
            }
            return padString.slice(0, targetLength) + String(this);
        }
    };
}

while(ids.length < 250) {
    let rnd = (Math.floor(Math.random() * 10000) + '').padStart(4, '0');
    if(ids.indexOf(rnd) === -1) ids.push(rnd);
}

fs.writeFile('list.txt', ids.join('\n'));