A class which can generate all possible combinations for a question with x true/false statements. For example, a question with 5 true/false statements can have 2^5 (32) possible combinations.

answer_generator.js

class AnswerGenerator {
    combinations = [];
    combinationNumber = -1;

    generateCombinations(numOfStatements = 5) {
        const combinations = [];
        const numOfPossibleCombinations = 2 ** numOfStatements;
        for (let i = 0; i < numOfPossibleCombinations; i++) {
            // for every number, convert it to binary
            const binary = i.toString(2); // 16 => 10000
            const padded = binary.padStart(numOfStatements, '0'); // 0 => 00000
            const combination = [];
            for (let j = 0; j < numOfStatements; j++) {
                if (padded[j] === '1') {
                    combination.push(true);
                } else {
                    combination.push(false);
                }
            }
            combinations.push(combination);
        }
        this.combinations = combinations;
        return combinations;
    }

    fillFormWithCombination() {
        if (!this.combinations.length) {
            throw new Error('Combinations must be generated first.');
        }
        // look in local storage after combination number
        let combinationNumber = localStorage.getItem('combinationNumber');
        if (combinationNumber) {
            // parse into integer
            combinationNumber = parseInt(combinationNumber, 10);
        }
        if (!combinationNumber || combinationNumber < 0) {
            // if it is was not set, or set to -1, set it to 0
            combinationNumber = 0;
        }
        this.combinationNumber = combinationNumber;
        const combination = this.combinations[combinationNumber];
        const checkboxes = document.querySelectorAll('input[type=checkbox]');
        for (let i = 0; i < combination.length; i++) {
            checkboxes[i].checked = combination[i];
        }
        this.combinationNumber++;
        localStorage.setItem('combinationNumber', this.combinationNumber.toString());
    }

    resetCombinationNumber() {
        this.combinationNumber = -1;
        localStorage.setItem('combinationNumber', -1);
    }
}

const answerGenerator = new AnswerGenerator();
answerGenerator.generateCombinations();
answerGenerator.fillFormWithCombination();