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JavaScript: Assignment Operators

Assignment Operators

An assignment operator assigns a value to its left operand based on the value of its right operand. The first operand must be a variable and basic assignment operator is equal (=), which assigns the value of its right operand to its left operand. That is, a = b assigns the value of b to a.

 In addition to the regular assignment operator "=" the other assignment operators are shorthand for standard operations, as shown in the following table.

Shorthand Expression Description
a +=b a = a + b Adds 2 numbers and assigns the result to the first.
a -= b a = a - b Subtracts 2 numbers and assigns the result to the first.
a *= b a = a*b Multiplies 2 numbers and assigns the result to the first.
a /=b a = a/b Divides 2 numbers and assigns the result to the first.
a %= b a = a%b Computes the modulus of 2 numbers and assigns the result to the first.
a<<=b a = a<<b Performs a left shift and assigns the result to the first operand.
a>>=b a = a>>b Performs a sign-propagating right shift and assigns the result to the first operand.
a>>>=b a = a>>>b Performs a zero-fill right shift and assigns the result to the first operand.
a&= b a = a&b Performs a bitwise AND and assigns the result to the first operand.
a^= b a = a^b Performs a bitwise XOR and assigns the result to the first operand.
a |=b a = a|b Performs a bitwise OR and assigns the result to the first operand.

Previous: JavaScript: Arithmetic Special Operators (%, ++, --, - )
Next: JavaScript: Bitwise Operators



JavaScript: Tips of the Day

JavaScript: semicolon (;)

function nums(a, b) {
  if (a > b) console.log('a is bigger');
  else console.log('b is bigger');
  return;
  a + b;
}

console.log(nums(4, 2));
console.log(nums(1, 2));

In JavaScript, we don't have to write the semicolon (;) explicitly, however the JavaScript engine still adds them after statements. This is called Automatic Semicolon Insertion. A statement can for example be variables, or keywords like throw, return, break, etc.
Here, we wrote a return statement, and another value a + b on a new line. However, since it's a new line, the engine doesn't know that it's actually the value that we wanted to return. Instead, it automatically added a semicolon after return. You could see this as:

return;
a + b;
This means that a + b is never reached, since a function stops running after the return keyword. If no value gets returned, like here, the function returns undefined. Note that there is no automatic insertion after if/else statements!

Ref: https://bit.ly/3jFRBje