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Why am I getting the error: "Uncaught TypeError: self.myTest is not a function"? How do I call a method from within another method in a javascript class?
class MyClass {
myTest() {
console.log('it works');
}
runMyTest() {
self.myTest();
}
}
var myClass = new MyClass();
myClass.runMyTest();
520
Many functional programming languages support method within method. But you can achieve nested method functionality in Java 7 or older version by define local classes, class within method so this does compile. And in java 8 and newer version you achieve it by lambda expression.
To call a function within class with Python, we call the function with self before it. We call the distToPoint instance method within the Coordinates class by calling self.
To call a method in Java, write the method name followed by a set of parentheses (), followed by a semicolon ( ; ). A class must have a matching filename ( Main and Main. java).
A method must be created in the class with the name of the method, followed by parentheses (). The method definition consists of a method header and method body. We can call a method by using the following: method_name(); //non static method calling.
You need to use the this keyword instead of self.
runMyTest() {
this.myTest();
}
A side note
If you are nesting standard functions notation then this is not lexically bound (will be undefined). To get around this, use Arrow Functions (preferred), .bind, or locally define this outside of the function.
class Test {
constructor() {
this.number = 3;
}
test() {
function getFirstThis() {
return this;
}
const getSecondThis = () => {
return this;
};
const getThirdThis = getFirstThis.bind(this);
const $this = this;
function getFourthThis() {
return $this;
}
// undefined
console.log(getFirstThis());
// All return "this" context, containing the number property
console.log(this);
console.log(getSecondThis());
console.log(getThirdThis());
console.log(getFourthThis());
}
}
new Test().test();You need to use this not self like
runMyTest() {
this.myTest();
}
However a lot of implementations like to keep the reference and are doing the following:
var self = this;
That might be the reason you were thinking of self as self reference. For further reading I'd suggest this SO - post
31
class MyClass {
myTest() {
console.log('it works');
}
runMyTest() {
this.myTest();
}
}
var myClass = new MyClass();
myClass.runMyTest();class MyClass {
myTest() {
console.log('it works');
}
runMyTest = ()=>{
this.myTest();
}
runMyTest2 = function(){
this.myTest();
}
}
var myClass = new MyClass();
myClass.runMyTest(); myClass.runMyTest2();
use arrow function to bind this to the global object. To represnt objects properties we have to use function
let user = {
name :"Something
}
user.value = ()=>{
console.log(this)
}
user.value2 = function(){
console.log(this)
}
user.value(); ///returns this for windows
user.value2(); ///returns object user
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