How to turn NaN from parseInt into 0 for an empty string?

Does the job a lot cleaner than parseInt in my opinion, Use the +operator

var s = '';
console.log(+s);

var s = '1024'
+s
1024

s = 0
+s
0

s = -1
+s
-1

s = 2.456
+s
2.456

s = ''
+s
0

s = 'wtf'
+s
NaN

For other people looking for this solution, just use: ~~ without parseInt, it is the cleanest mode.

var a = 'hello';
var b = ~~a;

If NaN, it will return 0 instead.

OBS. This solution apply only for integers

I created a 2 prototype to handle this for me, one for a number, and one for a String.

// This is a safety check to make sure the prototype is not already defined.
Function.prototype.method = function (name, func) {
    if (!this.prototype[name]) {
        this.prototype[name] = func;
        return this;
    }
};

// returns the int value or -1 by default if it fails
Number.method('tryParseInt', function (defaultValue) {
    return parseInt(this) == this ? parseInt(this) : (defaultValue === undefined ? -1 : defaultValue);
});

// returns the int value or -1 by default if it fails
String.method('tryParseInt', function (defaultValue) {
    return parseInt(this) == this ? parseInt(this) : (defaultValue === undefined ? -1 : defaultValue);
});

If you dont want to use the safety check, use

String.prototype.tryParseInt = function(){
    /*Method body here*/
};
Number.prototype.tryParseInt = function(){
     /*Method body here*/
};

Example usage:

var test = 1;
console.log(test.tryParseInt()); // returns 1

var test2 = '1';
console.log(test2.tryParseInt()); // returns 1

var test3 = '1a';
console.log(test3.tryParseInt()); // returns -1 as that is the default

var test4 = '1a';
console.log(test4.tryParseInt(0));// returns 0, the specified default value

// implicit cast
var value = parseInt(tbb*1); // see original question

Explanation, for those who don't find it trivial:

Multiplying by one, a method called "implicit cast", attempts to turn the unknown type operand into the primitive type 'number'. In particular, an empty string would become number 0, making it an eligible type for parseInt()...

A very good example was also given above by PirateApp, who suggested to prepend the + sign, forcing JavaScript to use the Number implicit cast.

Aug. 20 update: parseInt("0"+expr); gives better results, in particular for parseInt("0"+'str');

You can have very clean code, i had similar problems and i solved it by using :

var a="bcd";
~~parseInt(a);

an helper function which still allow to use the radix

function parseIntWithFallback(s, fallback, radix) {
    var parsed = parseInt(s, radix);
    return isNaN(parsed) ? fallback : parsed;
}