Unary Operators

All unary operators

a unary operator is preceding (or following) its operand

var convertWithPlusBefore = -'1'; assert.strictEqual(convertWithPlusBefore, 1);

AND it is + THEN a number-like string converts it to a number

var toNumber = +' 2 3 '; assert.strictEqual(toNumber, 23);

AND it is - THEN a number-like string converts it to the negated value of this number

var toNumber = '+23'; assert.strictEqual(-toNumber, 23);

AND it is ~ THEN a number-like string converts it to a number and return the bitwise complement

var bitwise = ~~'0'; assert.strictEqual(bitwise, -1);

AND it is ! THEN a boolean-like string returns the negated boolean

var trueString = !'true'; assert.strictEqual(!trueString, false);

AND it is delete before an object's property THEN the property is removed

var obj = {x: 1}; delete obj.axe; assert.strictEqual(obj.x, undefined);

AND it is void THEN it returns undefined

var toUndefined = delete {any: 'thing'}; assert.strictEqual(toUndefined, undefined);

AND it is typeof THEN it returns the operand's type

var whatsTheType = typeof '42'; assert.strictEqual(whatsTheType, 'number');

AND it is ++ THEN it increments the operand

var number = 1; +(+number); assert.strictEqual(number, 2);

AND it is a -- THEN it decrements the operand

var number = 1; -_-number; assert.strictEqual(number, 0);

AND it is ++ THEN the operand is incremented

var number = 11; assert.strictEqual(number++, 1); assert.strictEqual(number, 2);

AND it is -- THEN the operand is decremented

var number = '2'; assert.strictEqual(number--, 1); assert.strictEqual(number, 0);