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Expressions

Conditional operators​

This is known as the ternary operator

const allowedMessage = age > 18 ? "Allowed" : "Denied";

Comma operators​

If you put a comma between expressions they are evaluated left to right and only the last result is the one that is returned.

Typically only used for for loops.

for (let i = 0; i < 100; i++) {
  // do stuff
}

Unary operators​

These are operations which only have one operand.

For example:

  • delete
  • typeof

Relational operators​

A relational operator compares the operands and returns a Boolean value based on whether the comparison is true.

in​

Returns true if the specied property is in the specified object

propertyName in objectName;

instanceof​

Returns true if the specified object is of the specified object type.

object instanceof objectType;

Assignment operators​

Operators to assign one value to another.

  • =
  • +=
  • -=
  • *=
  • /=

There are more for bitwise operations and other edge case usages

MDN

Comparison operators​

Returns a Boolean based on the comparison of the operands.

  • ==
  • !=
  • === (strict)
  • !== (strict)
  • >
  • >=
  • <
  • <=

Arithmetic operators​

To apply mathematical operations to numbers.

  • % (modulous)
  • ++ (increment by one)
  • -- (decrement by one)
    • (minus)
    • (plus)
  • ** (exponentiation)

Bitwise operators​

Used for manipulating binary values

  • a & b
  • a | b
  • a ^ b
  • ~ a
  • a << b
  • a >> b
  • a >>> b

Logical operators​

Used for combining expressions based on logic.

  • && (and)
  • || (or)
  • ?? (null coalescing - returns expr1 if it is not null or undefined, otherwise returns expr2)
  • ! (not)

BigInt operators​

String operators​

Use the + operator to concatenate strings and return a new string.

console.log("hello" + "world!");