#Fixed math, the universe and everything in between ! Serverless compatible Math-Only JavaScript EVAL ! Introducing math eval - A math only eval that can actually calculate numbers unlike python and javascript lol, and does not require any library

evalMath.js

const evalMath = (str) => {
    const operatorToFunction = {
        "+": (a, b) => a + b,
        "-": (a, b) => a - b,
        "*": (a, b) => a * b,
        "/": (a, b) => a / b
    };
    const operationStr = str.replace(/\s/g, '');
    const numbers = operationStr.split(/[-+*/]/).map(Number);
    const operators = operationStr.split(/\d+/).filter(Boolean).filter(operator => operator !== '.');
    for (let i = 0; i < operators.length; i++) {
        const operator = operators[i];
        const nextNumber = numbers[i + 1];
        if (operator === '*' || operator === '/') {
            numbers[i] = operatorToFunction[operator](numbers[i], nextNumber);
            numbers.splice(i + 1, 1);
            operators.splice(i, 1);
            i--;
        }
    }
    let result = numbers[0];
    for (let i = 0; i < operators.length; i++) {
        const operator = operators[i];
        const nextNumber = numbers[i + 1];
        result = operatorToFunction[operator](result, nextNumber);
    }
    const numberString = result.toFixed(15);
    const decimalIndex = numberString.indexOf('.');
    let trimmedNumberString = numberString;
    if (decimalIndex !== -1) {
        let i = numberString.length - 1;
        while (numberString[i] === '0' && i > decimalIndex) {
            i--;
        }
        trimmedNumberString = numberString.substring(0, i + 1);
        if (trimmedNumberString.charAt(trimmedNumberString.length - 1) === '.') trimmedNumberString = trimmedNumberString.slice(0, -1);
    }
    const finalResult = parseFloat(trimmedNumberString);
    // test: (compares itself to eval)
    const DEBUG = true;
    if (DEBUG) {
        const PERFORM_TEST = false; // <<<<< enable this
        if (!PERFORM_TEST) {
            console.log(str, '=', finalResult)
        } else {
            const ONLY_SHOW_INVALID = false;
            try {
                const evalResult = eval(str);
                const numberString2 = evalResult.toFixed(15);
                const decimalIndex2 = numberString2.indexOf('.');
                let trimmedNumberString2 = numberString2;
                if (decimalIndex2 !== -1) {
                    let i2 = numberString2.length - 1;
                    while (numberString2[i2] === '0' && i2 > decimalIndex2) {
                        i2--;
                    }
                    trimmedNumberString2 = numberString2.substring(0, i2 + 1);
                    if (trimmedNumberString2.charAt(trimmedNumberString2.length - 1) === '.') trimmedNumberString2 = trimmedNumberString2.slice(0, -1);
                }
                const finalEvalResult = parseFloat(trimmedNumberString2);
                const isValid = finalResult === finalEvalResult;
                if (ONLY_SHOW_INVALID) {
                    if (!isValid) console.log(str, '=', finalResult, 'Invalid: ' + finalEvalResult)
                } else {
                    console.log(str, '=', finalResult, "Is Valid?", isValid, isValid ? 'Valid' : 'Invalid: ' + finalEvalResult)
                }
            } catch(e) {
                console.warn("Eval Error:", str, e.message);
            }
        }
    }
    // you can remove the test (which uses eval to verify itself) ^^
    return finalResult;
};

let example;
example = evalMath('1 + 1');
example = evalMath('4 - 1');
example = evalMath('2 * 5');
example = evalMath('16 / 4');
example = evalMath('1 + 1 + 2');
example = evalMath('4 - 1 - 2');
example = evalMath('15 * 1000 * 2 / 2 * 2');
example = evalMath('1 + 15 * 1000 * 2 / 2 * 2');
example = evalMath('15 * 1000 * 2 / 2 * 2 + 1');
example = evalMath('16 / 4 / 2');
example = evalMath('5 * 5');
example = evalMath('10 / 2');
example = evalMath('3 + 5 * 2');
example = evalMath('3 * 5 + 2');
example = evalMath('10 - 3 * 2 + 5');
example = evalMath('10 - 3 * 2');
example = evalMath('3 * 2 + 5');
example = evalMath('2 * 3 + 5 * 4');
// example = evalMath('2 * (3 + 5)'); // Error
// example = evalMath('a + a'); // Error
// example = evalMath('b'); // Error
example = evalMath('0');
example = evalMath('20');
example = evalMath('-10 + 10');
example = evalMath('-10 + 12');
example = evalMath('10 - 15');
// example = evalMath('1-'); // Error
example = evalMath('-1');
example = evalMath('10 / 3');
example = evalMath('1+1+1*2+1+1+1');
example = evalMath('2.5 * 5');
example = evalMath('1.5 + 1.5');
example = evalMath('4.5 - 1.2');
example = evalMath('2.3 * 2.5');
example = evalMath('16.8 / 4.2');
example = evalMath('1.1 + 1.2 + 2.3');
example = evalMath('4.5 - 1.2 - 2.1');
example = evalMath('15.25 * 100.5 * 2.2 / 2.5 * 2.5');
example = evalMath('1.1 + 15.5 * 100.25 * 2.2 / 2.1 * 2.1');
example = evalMath('15.5 * 1000.2 * 2.1 / 2.5 * 2.5 + 1.5');
example = evalMath('16.5 / 4.5 / 2.5');
example = evalMath('5.5 * 5.5');
example = evalMath('10.5 / 2.5');
example = evalMath('3.5 + 5.5 * 2.5');
example = evalMath('3.2 * 5.5 + 2.5');
example = evalMath('10.5 - 3.2 * 2.5 + 5.5');
example = evalMath('10.5 - 3.2 * 2.5');
example = evalMath('3.5 * 2.5 + 5.5');
example = evalMath('2.1 * 3.5 + 5.5 * 4.5');
example = evalMath('2.5 * 5.2');
example = evalMath('0.1');
example = evalMath('20.2');
example = evalMath('-10.5 + 10.5');
example = evalMath('-10.5 + 12.2');
example = evalMath('10.5 - 15.5');
// example = evalMath('1.1-'); // Error
example = evalMath('-1.1');
example = evalMath('10.5 / 3.5');
example = evalMath('1.2+1.3+1.5*2.5+1.7+1.8+1.9');
"Finished"

To solve the python one just use:
format(3.3-2.1, '.1f')

or

from decimal import Decimal
result = Decimal('3.3') - Decimal('2.1')
print(result)