There are many Comparison Operators in JavaScript. All of these operators return a boolean true or false value.

The most basic operator is the equality operator ==. The equality operator compares two values and returns true if they're equivalent or false if they are not. Note that equality is different from assignment (=), which assigns the value at the right of the operator to a variable in the left.

function testEqual(myVal) {
  if (myVal == 10) {
     return "Equal";
  }
  return "Not Equal";
}

If myVal is equal to 10, the function will return "Equal". If it is not, the function will return "Not Equal".

The equality operator will do its best to convert values for comparison, for example:

   1   ==  1        // true
  "1"  ==  1        // true
   1   == '1'       // true
   0   == false     // true
   0   == null      // false
   0   == undefined // false
 null  == undefined // true