Rest parameters are similar to Javascript's arguments object, which is

an array-like object that contains all of the parameters (named and

unnamed) in the current function call. Unlike arguments, however, rest

parameters are true Array objects, so methods such as .slice() and

.sort() can be used on them directly.

| == | equal |

|---|---|

| != | not equal |

| > | greater than |

| >= | greater than or equal to |

| < | less than |

| <= | less than or equal to |

| === | identical (equal and of same type) |

| !== | not identical |

Variables referencing objects are equal or identical only if they

reference the same object:

const obj1 = {a: 1};

const obj2 = {a: 1};

const obj3 = obj1;

console.log(obj1 == obj2); //false

console.log(obj3 == obj1); //true

console.log(obj3 === obj1); //true

See also String.

JavaScript provides four logical operators:

• unary negation (NOT = !a)

• binary disjunction (OR = a || b) and conjunction (AND = a && b)

• ternary conditional (c ? t : f)

In the context of a logical operation, any expression evaluates to true

except the following:

• Strings: "", '',

• Numbers: 0, -0, NaN,

• Special: null, undefined,

• Boolean: false.

The Boolean function can be used to explicitly convert to a primitive of

type Boolean:

// Only empty strings return false

console.log(Boolean("") === false);

console.log(Boolean("false") === true);

console.log(Boolean("0") === true);

// Only zero and NaN return false

console.log(Boolean(NaN) === false);

console.log(Boolean(0) === false);

console.log(Boolean(-0) === false); // equivalent to -1*0

console.log(Boolean(-2) === true);

// All objects return true