Tag Archives: xtypeof

JavaScript: Make a Real typeof

The problems with JavaScript’s typeof operator are manifold. It is so restricted, that its only use is in testing for undefined. The main culprit cause these restrictions is the loose typing together with the automatic type coercion: "2" + 2 results in 22, "2" == 2 is true, t = 2;typeof t returns "number" and t = new Number(2);typeof t returns "object" to name just a few.
The worst case is probably:

// somewhere on top of the code
var a = 2;
// some thousand lines and/or several scripts later
var b = new Number(2);
if(a === b){
    // CPR: Cardiopulmonary resuscitation
    console.log("Go on with CPR!");
} else {
    console.log("He's dead, Jim!"),
}

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