JavaScript syntax
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console.log(!"s" === Boolean(!"s"));
The ternary operator can also be used for explicit conversion:
console.log([] == false); console.log([] ? true : false); // “truthy”, but the comparison uses [].toString()
console.log([0] == false); console.log([0]? true : false); // [0].toString() == "0"
console.log("0" == false); console.log("0"? true : false); // "0" → 0 ... (0 == 0) ... 0 ← false
console.log([1] == true); console.log([1]? true : false); // [1].toString() == "1"
console.log("1" == true); console.log("1"? true : false); // "1" → 1 ... (1 == 1) ... 1 ← true
console.log([2] != true); console.log([2]? true : false); // [2].toString() == "2"
console.log("2" != true); console.log("2"? true : false); // "2" → 2 ... (2 != 1) ... 1 ← true
Expressions that use features such as post–incrementation (i++) have an anticipated side effect. JavaScript provides short-circuit evaluation of expressions; the right operand is only executed if the left operand does not suffice to determine the value of the expression.
console.log(a || b); // When a is true, there is no reason to evaluate b.
console.log(a && b); // When a is false, there is no reason to evaluate b.
console.log(c ? t : f); // When c is true, there is no reason to evaluate f.
In early versions of JavaScript and JScript, the binary logical operators returned a Boolean value (like most C-derived programming languages). However, all contemporary implementations return one of their operands instead:
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