“Conditions” memo

Syntax

Condition:

if (condition) {
  action;
}

Condition with alternative action:

if (condition) {
  actions;
} else {
  other actions;
}

Nested conditions:

if (condition1) {
  if (condition2) {
    actions;
  }
}

How Conditions Work

Expression in parentheses (check) returns true or false. The action inside the condition is executed if true is returned. If the expression returns false, the action will not be executed.

Code inside the checks

Comparison operators:

OperatorName
>more than
<less than
>=more than or equal to
<=less than or equal to

Equality operators:

OperatorNameDescription
==approximate equalitywith casting argument types
===strict equalitywithout casting argument types
!="approximate inequality"with casting argument types
!==strict inequalitywithout casting argument types

Any values ​​within the checks are converted to Boolean datatype. All numbers except 0 are true, with 0 being false. All lines except the empty string are true, empty string '' is false.

Logical operators.

  • The && operator or “logical AND” returns true only if both conditions, to the left and right of it, return true.
  • The operator || or “logical OR” returns true if any of the conditions to the left or to the right of it return true.
  • The ! operator or “logical negation” changes the Boolean value of the expression to the right of it to the opposite value.

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