Type checker for JavaScript?

Question

Does anyone know if there\'s a good tool for analyzing JavaScript code and detecting type errors? I know that JavaScript itself is weakly and dynamically typed, but it woul

Answer 1

Below is a basic example on how to do type checking in JavaScript:

const Int = (val) => {
    if (Number.isInteger(val)) {
        return val;
    }else {
        throw new TypeError(`Argument value ${val} is not integer`);
    }
    return 0; //Unreachable: for static analysis
};

const sum = function(_, numA = Int(_[0]), numB = Int(_[1])) {
    return `Sum is ${numA + numB}`;
};

console.log(sum([1, 2])); //correct
console.log(sum([1, "2"])); //incorrect