safeMath.js

function safeMath(example) {
	const numbersRegX = /[0-9]+(\.[0-9]+|)?/g;
	const replaceData = [];
	example.replace(numbersRegX, function() {
		replaceData.push(arguments);
	});

	const maxFract = replaceData.reduce((max, [,fract]) => {
		if (fract && max < fract.length) {
			max = fract.length;
		}
		return max;
	}, 1);

	const commonDelimer = `1${'0'.repeat(maxFract)}`;

	const modifiedExample = example.replace(numbersRegX, function(match) {
		return `(${match} * ${commonDelimer})`;
	});

	const result = eval(`(${modifiedExample})/${commonDelimer}`);

	return result;
}


// example of use
safeMath('0.1 + 0.2'); // => 0.3
// bugs:
//    2*3
//    2/4