Typescript allows use of static variables and methods just like modern Javascript.
Static variables and methods are declared with a keyword static.
Static variables
Static variables exist within the class context, and are not carried forward to the object of the class.
Define a static variable like so -
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class Human {
static chaos: boolean = true;
}
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The variable value is accessible using the class.
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console.log(Human.chaos);
// true
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.. but not against the object.
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const joe = new Human();
console.log(joe.chaos);
// error TS2576: Property 'chaos' is a static member of type 'Human'
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If you need a value in the object no matter the costs, you can always have the two variables with same names.
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class Human {
static chaos: boolean = true;
chaos: boolean = true;
}
console.log(Human.chaos);
// true
const joe = new Human();
console.log(joe.chaos);
// true
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Static methods / members
Static methods behave similar to static variables.
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class Human {
static chaos: boolean = true;
chaos: boolean = true;
static checkExists(): string {
return "exists";
}
doubleCheckExists(): string {
return "exists";
}
}
console.log(Human.checkExists());
// exists
// console.log(Human.doubleCheckExists());
// error - cannot call a instance member
const joe = new Human();
console.log(joe.doubleCheckExists());
//exists
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Note that static variables cannot be called by instance members and vice-versa.
Static variables / members are distinct from their instance counterparts at all times.
