Parsing and converting exponential values to decimal in JavaScript

Question

I want to parse and convert an exponential value into a decimal using JavaScript. 4.65661287307739E-10 should give 0.000000000465661287307739. What

Answer 1

This variant works well for me to display formatted string values for too small/big numbers:

const exponentialToDecimal = exponential => {
    let decimal = exponential.toString().toLowerCase();
    if (decimal.includes('e+')) {
        const exponentialSplitted = decimal.split('e+');
        let postfix = '';
        for (
            let i = 0;
            i <
            +exponentialSplitted[1] -
                (exponentialSplitted[0].includes('.') ? exponentialSplitted[0].split('.')[1].length : 0);
            i++
        ) {
            postfix += '0';
        }
        const addCommas = text => {
            let j = 3;
            let textLength = text.length;
            while (j < textLength) {
                text = `${text.slice(0, textLength - j)},${text.slice(textLength - j, textLength)}`;
                textLength++;
                j += 3 + 1;
            }
            return text;
        };
        decimal = addCommas(exponentialSplitted[0].replace('.', '') + postfix);
    }
    if (decimal.toLowerCase().includes('e-')) {
        const exponentialSplitted = decimal.split('e-');
        let prefix = '0.';
        for (let i = 0; i < +exponentialSplitted[1] - 1; i++) {
            prefix += '0';
        }
        decimal = prefix + exponentialSplitted[0].replace('.', '');
    }
    return decimal;
};

const result1 = exponentialToDecimal(5.6565e29); // "565,650,000,000,000,000,000,000,000,000"
const result2 = exponentialToDecimal(5.6565e-29); // "0.000000000000000000000000000056565"