javascript switch() or if()

Question

which would be better if i do this:

if(message == \'redirect\')
{
    is_valid.accepted = true;
}
else if(message == \'invalid id\')
{
    is_valid.accepted          


        

Answer 1

The switch statement is more efficient/expressive than if/else in some cases. While the following if/else statement

let x = 123;

if (x) {/*...*/} // implicit type casting (to boolean)
else {/*...*/}

can be easily converted to:

switch (!!x) { // explicit type casting (to boolean)
  case true: /*...*/ break;
  default: /*...*/
}

this switch statement on the other hand

function algo(x) {/*...performing a complex algorithm...*/}

switch (algo(123)) { // executed once
  case "result 1": /*...*/ break;
  case "result 2": /*...*/ break;
  case "result 3": /*...*/ break;
  default: /*...*/
}

results in an incredible inefficient if/else statement (switch is more efficient):

if (algo(123) === "result 1") {/*...*/}
else if (algo(123) === "result 2") {/*...*/}
else if (algo(123) === "result 3") {/*...*/}
else {/*...*/}

or requires an if/else with additional variable, which is declared for this purpose exclusively:

let y = algo(x); // additional variable

if (y === "result 1") {/*...*/}
else if (y === "result 2") {/*...*/}
else if (y === "result 3") {/*...*/}
else {/*...*/}

Please note that additional elements (like variables) cause more complexity and complexity makes programs more error prone. The switch statement doesn't need such a variable, because it is more expressive.