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How Do I Target A Specific Node In React Component and Have Independent Behavior When Component is Reused?

I am trying to target a specific node in my react reusable component and perform an operation on it. But I want to be able to do same thing several times independently because I will be returning this my reusable component several times on the same page on my App.js. How do I target that div node uniquely?
Here is my situation:
I created a react class component (I am not using function component for this project). This component contains two divs and a button. The first div is a red box. Under it is the second div which is empty with the class "result". There is also a button. When I click this button, the package Html2Canvas will convert the first div into an image and append it to the second div.
Now from the Html2Canvas documentation, they only specified how to append the generated canvas to the body of the DOM:
html2canvas(document.querySelector("#capture")).then(canvas => {
document.body.appendChild(canvas)
});
Since I needed to append to that empty second div, I did:
html2canvas(document.querySelector("#capture")).then(canvas => {
document.queryselector('.result').appendChild(canvas)
});
This would have been fine if I am just using this component once on a page, but in my App.js, I am actually returning this my component multiple times, so what now happens is that each time I click that button, it targets only the first instance of the empty whereas what I need is that each occurrence of my component should behave like the first one independently.
Yes I have tried using CreateRef() to target the current occurrence oof the empty dive but it does not work. It sees the ref as undefined when I call it inside the Html2Caanvas function. But outside of it, it is defined. Ok I tried creating the ref inside, still gave an error of undefined.
I understand that this whole thing I have written may be somewhat vague, so here is a CodeSandBox example of what I want.
When you open it and click on the first "Finish" button, you will see that the red box gets converted to an image, and the image is added under the red box, that is, it is appended to the div with class "result". But when you click on the second "Finish" button, instead of the generated image of the blue box coming under the blue box div, it goes under or beside the previous image. The expected behavior is for it to appear under the blue box. And if I replicate that component "ReUsable" as many times as I want in the App.js, the same behavior is expected. Independence.
I know this is a lot. I look forward to and appreciate your solutions.

First, the ref approach was great (the one you commented out), only that you were referencing the containerRef and not the screenshotRef.
the main issue came from the callback function passed to html2canvas, even though you called bind on handleFinish, binding "this" context to the current class context, the execution context of "this" in the callback is undefined because you used a regular function and regular function always refers to the context of the function being called(html2canvas).
arrow functions on the other hand treat the "this" keyword differently. They don't define their own context.
kindly update your handleFinish method to this
handleFinish(event) {
html2canvas(this.containerRef.current, 1).then((canvas) =>{
this.screenshotRef.current.append(canvas);
// document.querySelector(".result").append(canvas);
});
}

How do I get an input with v-model to update when the Vue route changes?

I have the following code:
https://jsfiddle.net/audiodude/pq9aczdu/33/
If you go to the Item View, then jump to page 10, say, it displays "page 10 of ??" (you're on page 10) and the input box agrees.
If you jump to page 20, same thing, so far so good.
However, if you then use the back button in your browser, it says "page 10 of ??" but the input box still says page 20.
I know that the Vue Router likes to reuse components when the path doesn't change, and my understanding is that the "this.page" data value on the ItemPagination component isn't getting updated. But I thought I was following good practice by separating the initialPage prop from the data that is bound to the model.
How do I get the input box to update on the browser BACK action? I can't use onBeforeRouteUpdate on ItemPagination because it's not the top level component being rendered so never receives that event.
Thanks!

Add the following to your ItemPagination component to keep an eye on changes to the route and query parameters
watch: {
$route (to) {
this.page = to.query.page || 1
}
}
See https://router.vuejs.org/guide/essentials/dynamic-matching.html#reacting-to-params-changes

how can I Re-position after editing a table value in React?

There is an UI I have created using React. There are two text fields to enter value, after entering and saving those values will be populated in a table below the two fields(we are using antd for designing).
However when I click a single record in the table and click edit in that particular record data from that record will be populated to the above mentioned text fields. When this happens I want my app to scroll up and show those two text fields which are ready to be edited.
But currently it stays at the same position after clicked edit, without scrolling up and showing two text fields. Here's an image descripting my experience

Check this answer to find how to control srollTop: https://stackoverflow.com/a/55184755/2360631
But I don't think it's a good idea, maybe you can consider to freeze the edit area otherwise when you finish edit you may need to scroll back again...

Basically you want to set focus to some component after a re-render.
To refer to a particular component, use react refs
make a react ref of whatever you want to set focus to and assign it as a ref prop
constructor() {
super();
this.foo = React.createRef();
}
componentDidUpdate() {
this.foo.current.focus();
}
<Bar ref={this.foo}> .... </Bar>
foo is the name of ref
Bar is the component you want to set focus to
in your case it can be a parent of both input fields or any one of the input fields

React/JSX - how to code an editable input with initial content provided via props that only updates its parent when submitted?

All the examples I have found that keep local state can't provide an initial value for the input. In my case a parent component retrieves field from a server and passes these to my input form where the fields shall be editable. But I don't want to pass each change back up the hierarchy if I can avoid it, rather only when the form is submitted (either via button or by pressing enter)
Update: the usage is as follows. Imagine a todo list. The top level holds the list and the detail component. When I click at the list the detail should update to show the selected todo text. That text should be editable.
So as far the the detail component goes the initial state of the input is the text from the list that gets passed down in props. It needs to change when a different todo in the list is selected. On the other hand I should be able to edit it and when submit triggered that todo text should be passed back up via a callback prop.
So I have to keep local state to collect the input, but I want that state to be initialized with the existing todo text from the list. If I use the Facebook example of an uncontrolled form, I find the edited text remains displayed when I switch to a different todo in the list. Maybe I'm doing it wrong or is it a conceptual problem? Using controlled input initializing the state in the constructor doesn't work either because the constructor only gets called once (not on each re-render)!

I solved the problem by using the lifecycle method componentWillReceiveProps(nextprops) where I can set the state to the new props. This method gets called each time a re-render becomes necessary - in my case because the parent changes the childs props.
See https://facebook.github.io/react/docs/react-component.html#componentwillreceiveprops

You can set the initial state based on the property passed in from the parent, then edit that state in the component before submitting with the form submission

How to programmatically add components or views inside other components/views in ember js

I have a component say {{component-1}} which gets called many times and creates a custom-texbox container and label as many times as it gets called.
Now whenever a user writes something in it a suggestion box should appear below it. Since the suggestion box can be reused everywhere i dont want to have a separate suggestion box for each {{component-1}}, rather i want to have another component called {{suggestion-box}} that gets inserted inside component-1 i.e. the textbox container.
I dont want {{suggestion-box}} to be inside dom at all since it is needed only when somebody types in it. I want to add/insert it into {{component-1}} when someone types. Instead of a component i even tried to use a view
Here are the different things i have tried and failed
Note:
suggestionBox is the component
textbox-container is an element inside {{component-1}}
Inside {{component-1}}this.$().find(".textbox-container").append(this.suggestionBox );where this.suggestionBox = suggestionBoxComponent.create(); I have event tried suggestionBoxView.create();It gives me the error that i one view cant be inserted into another and i need to use containerView
var tmp = Ember.Handlebars.compile('<div class=".suggestionBox"></div>');this.$().find('.textbox-container').append(tmp());I get the error called
Uncaught TypeError: Cannot read property 'push' of undefined
I even tried to use view instead of component i.e. make suggestionBox a view but then again i cannot insert one view inside another
I have tried a lot more things.
Few points:
I dont want alternate solutions of how textbox and suggestion box could be created
How to pass information from a component or a a template to a view? Say i do {{view "suggestion-box"}} inside component-1 template, how do i pass values to it? Say for components we pass in the context like this {{component1 sampleVar1=val1 sampleVar2=val2}}
i Want to know how to programmatically add a component or a view and if it is a view how to pass the data to it?
I dont want to use container-view since it will cause more complexities, however if your solution allows me to pass value from {{component-1}} to container-view and inturn pass it to corresponding childView1 and childView2 then that solution is acceptable
Just an update:
I even tried to use a view container inside the {{component-1}}
I also tried to use view block inside {{component-1}} i.e.
{{#view "view-name"}}
----earlier component elements here-----
{{/view}}
In both the above points "view-name" is a ContainerView which is getting inserted properly but the component element are not getting inserted

This can be achieved with a ContainerView and the viewName attribute. The component or view can access the ContainerView or any other view that is part of a template through its assigned viewName.
Example,
hbs
{{view Ember.ContainerView viewName="my-menu-container"}}
js - then from the component or view
this.get("my-menu-container").pushObject(suggestionBoxViewOrComponent);
http://emberjs.jsbin.com/yoyujeqi/1/edit
p.s. the context of the example is not relevant to the suggestion box, sorry about that, as it has been extracted from another answer related to adding a menu view dynamically.