These are JavaScript's special/miscellaneous operators that don't fit neatly into arithmetic, comparison, or logical categories.
delete[]
Deletes any properties or objects passed to it. Returns true if the deletion was successful.
delete object.property; delete object["property"];
in[]
Used in two contexts:
- In for...in loops, assigns each successive index owned by the right object into the left variable
- Everywhere else, returns a Boolean representing whether the right object has a property by the name of the left identifier
"property" in object; // true or false
for (var key in object) { ... }
instanceof[]
Returns a Boolean representing whether the first value is an instance of the right constructor.
value instanceof Constructor; // true or false
new[]
Returns a new instance of the constructor operand.
var obj = new Constructor();
typeof[]
Returns a string representing the argument's type. The possible return values cover only a subset of the literal types:
void[]
A legacy feature that returns undefined regardless of its operand. Occasionally used to suppress return values in javascript: URLs or to wrap a statement explicitly.
void 0; // returns undefined void(expr); // evaluates expr, returns undefined