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Stop a setInterval inside its callback [closed]

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Does anyone have any idea how to stop an interval that is situated inside of a function once it's done doing its thing?
Here is what I mean:
function renderMessage(message) {
const renderInterval = setInterval(() => {
characterIndex++;
dealerMessage.innerHTML = `
${messages[message].slice(0, characterIndex)}
`;
if (characterIndex === messages[message].length) {
clearInterval(renderInterval)
}
}, 100);
}
As you can see, I'm trying to render out a message using this function. It does its job fine, but if I don't stop it, subsequent messages keep overriding themselves...
I've tested the if check and it is actually functioning inside the function, yet for some reason the clearInterval doesn't work.
Is there any way I can fix this, or do you recommend me to start from scratch?
Note: this method would be very handy for me, so, if possible, I would like to keep it.

I think your 'if' statement of clearInterval should be
if (characterIndex===message[message.length]){}
Also, I cannot see any initialization of the characterIndex variable. Please do inform if this worked or not.

Iterate over array in proxy [closed]

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Good day.
I was testing stuff in Javascript with Proxies.
Currently I have this proxy
My question was, how do I iterate over this? I've tried several methods, including object.keys and forEach, which yielded nothing.
Thanks in advance

You need to specify an ownKeys method in the handler you're using to create the proxy or you won't be able to enumerate the keys of the proxy object.
const obj = { test: 'a' };
const handler1 = {
ownKeys(target) {
return Reflect.ownKeys(target);
}
};
const proxy1 = new Proxy(obj, handler1);
console.log(Object.keys(proxy1)) // ['test']
Edit
Actually, you can use Reflect.ownKeys directly also, but you'll want to make sure the behavior is what you expect. For example, it might return length as a key as well.

I was taking a challenge [closed]

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I was taking a challenge and one of the questions seems like I got the right answer but it wouldn't pass. Need help understanding why it didn't.
Challenge: Add a method to the Person's prototype called "shoutName" that returns the person's name in all uppercase letters.
function Person(name) {
this.name = name;
this.shoutName = function() {
name.toUpperCase();
return '"' + name.toUpperCase()+'"'
}
}
/* Do not modify the code below this line */
const john = new Person('John');
console.log(john.shoutName(), '<-- should be "JOHN" ');

The question said to add a function to the constructor's prototype.
You didn't do that. You modified the constructor to dynamically add the function to the instance as the instance was created.
Person.prototype.shoutName = function () {
return this.name.toUpperCase();
}
Your function also wrapped the resulting value in quotes, which the question didn't ask you to do.

From your tiny picture, I noticed that your code was:
return '"' + name.toUpperCase() + '"';
Not sure why you added the quotes, just return this.name.toUpperCase(); and it should work fine. You should be referencing this object's property, rather than the input value of just name.
Also, having name.toUpperCase(); on a line by itself does nothing. Unnecessary calculations since that function returns a value that you're not assigning.

Is it bad to have If-instanceof-statements in Typescript? [closed]

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selectAction: (actionEvent) => {
if (actionEvent instanceof Action1) {
// action1 body implementation
} else if (actionEvent instanceof Action2) {
// action2 body implementation
}
}
The above code snippet reflects that different types of action which does different functionalities.I have used if and else condition to check action.
I feel it's not a good solution since I might have more actions in the future and my if-else-ladder will keep growing and I need to update my code again when there is a change.
Any idea on improving this specific scenario?

Use the approach of duck typing to avoid conditional scenarios. Source
Have a method called selection() inside each type instance Action1 and Action2 so- on and use that to define the body/desired functionality you want to build. And simply call selection() method avoiding condition. So based on the instance of the type it will call the correct selection() method of the corresponding type

There's nothing inherently wrong with using if/else in TypeScript.
However, when you're using instanceof, the odds are that you probably have a better option available. In this case, almost certainly, the actions themselves should be responsible for doing what they do:
selectAction: (actionEvent) => {
actionEvent.execute();
}
...or
selectAction: (actionEvent) => {
const action = /*...derive action from actionEvent...*/;
action.execute();
}
...or similar (or of course, use actionEvent.execute() directly instead of selectAction).
This is fundamentaly polymorphism, having different objects conforming to the same interface, and doing (potentially) different things when called.

Adding item into an array with push function [closed]

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screenshot
Can someone verify where I went wrong?

addTodos parameter todos will override the global todos so just rename it to something else. see below example
var todos = ['1','2','3'];
function display() {
console.log(todos)
}
function addTodos(todo) {
todos.push(todo)
display()
}
addTodos('4')

The problem you are having with your code is, you created a global variable var todos and at the same time in your addTodos function you added an argument todos, the JavaScript is accessing your function argument not the global variable,
Now change the name of the global variable, to something like var myTodos to avoid conflicting
Hope this helps 😉

todos is a string not an array where error is occurring.
string type doesn't have push method. Also, local todos is found first in the local scope so it masks the array version.

Not sure whether you have realised, you are sending in an argument called todos. You are effectively overwriting the todos array that has been set previously. Replacing it with a new variable name would fix the problem
function addTodos(newTodo) {
todos.push(newTodo);
}