Truth, Equality and JavaScript

 
You don’t have to be a JavaScript novice to get confused by this…

if ([0]) {
    console.log([0] == true); //false
    console.log(!![0]); //true
}

 
or this…

if ("potato") {
    console.log("potato" == false); //false
    console.log("potato" == true); //false
}

 
The good news is that there is a standard and all browsers follow it. Some authors will tell you to fear coercion and and code against it. I hope to persuade you that coercion is a feature to be leveraged (or at the very least understood), not avoided…

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The Secret Life of JavaScript Primitives

You may not know it but, in JavaScript, whenever you interact with string, number or boolean primitives you enter a hidden world of object shadows and coercion. So dust off your Sherlock Holmes outfit and read on…