Go if

The if statement specifies the conditional execution of two branches according to the value of a boolean expression. Optionally, the boolean expression may be preceded by another statement, which is executed before the expression is evaluated.

Simple If

https://go.dev/ref/spec#If_statements

if <condition> {
  <statements>
}

if x > 5 {
  println(x)
}

If/else

if <condition> {
  <statements>
} else {
  <statements>
}

if x > 5 {
  println(x)
} else {
  println("something else")
}

A special if syntax supports the Go error handling idiom that relies on functions returning errors as result value:

var result ...
var err error
if result, err = someFunc(); err != nil {
  // handle error
  return
}
// handle success
...

Avoid else in the idiom above. Do NOT write this:

if result, err := someFunc(); err {
  // handle error
  ...
} else { // BAD, avoid the "else"
  // handle success
  ...  
}

If/else if/else

if <condition> {
  <statements>
} else if <condition> {
  <statements>
} else {
  <statements>
}

if x < 5 {
  println(x)
} else if x == 5 {
  println("is 5")
} else {
  println("something else")
}