state

In React I am trying to make a button increment a value stored in state. However using the code below function my value is set undefined or NaN when using handleClick. class QuestionList extends React.Component { constructor(props) { super(props); this.state = {value: 0}; // This binding is necessary to make `this` work in the callback this.handleClick = this.handleClick.bind(this); } handleClick = (prevState) => { this.setState({value: prevState.value + 1}); console.log(this.state.value) } Can you tell me why this is happening? it should be correct according to the docs here: https://facebook

So I started learning React a week ago and I inevitably got to the problem of state and how components are supposed to communicate with the rest of the app. I searched around and Redux seems to be the flavor of the month. I read through all the documentation and I think it's actually a pretty revolutionary idea. Here are my thoughts on it: State is generally agreed to be pretty evil and a large source of bugs in programming. Instead of scattering it all throughout your app Redux says why not just have it all concentrated in a global state tree that you have to emit actions to change? Sounds

I have been instructed by my professor to introduce myself on a page as if I were an object, and that I must address three things: 1) Object State, 2) Behavior, and 3) Identity. However, I am still really confused as to how I would go about doing something like this. (I have read about the three attributes I must address, but I don't know how I would apply it to a person). For example, I was told a dog would have States, such as name, color, and breed; as well as Behaviors, such as walking, barking, or wagging their tail. So would I do something similar to: Student me = new Student(); System

Suppose I have a state monad such as: data Registers = Reg {...} data ST = ST {registers :: Registers, memory :: Array Int Int} newtype Op a = Op {runOp :: ST -> (ST, a)} instance Monad Op where return a = Op $ \st -> (st, a) (>>=) stf f = Op $ \st -> let (st1, a1) = runOp stf st (st2, a2) = runOp (f a1) st1 in (st2, a2) with functions like getState :: (ST -> a) -> Op a getState g = Op (\st -> (st, g st) updState :: (ST -> ST) -> Op () updState g = Op (\st -> (g st, ())) and so forth. I want to combine various operations in this monad with IO actions. So I could either write an evaluation loop

I am using SharedPreference to store the state of checkboxes but even i am storing true in it , its still retrieving false. Here is my code - @Override public void onPause() { super.onPause(); saveState(); } @Override public void onResume() { super.onResume(); loadState(); } @Override public void onRestart() { super.onRestart(); loadState(); } public void saveState() { SharedPreferences sp = getPreferences(Context.MODE_PRIVATE); SharedPreferences.Editor editor = sp.edit(); for(int i = 0; i < itemCheck.length; i++) { Boolean b = itemCheck[i]; Log.e(TAG, b.toString()); editor.putBoolean(i+"",

I am trying to find a way to remove a few US states from the "State" dropdown in WooCommerce checkout page. List of states: Hawaii Alaska Armed Forces (AA) Armed Forces (AE) Armed Forces (AP) What I have been doing so far: I have been manually removing them as mentioned in this link . But this is not a good way, as the changes get overwritten every time WooCommerce is updated. Alternative I found: On this link WooCommerce restrict shipping to states based on category , there's a way to set shipping states if specific condition is met. I am wondering if I can unset five states. This sounds more

I have two calendars, such as the Agenda, have an icon calendar button, when I click on it, it will be redirected to another calendar (Planning) , these calendars are developed with react-big-calendar , I want when I navigate for example on the week of juin 17 - 23 of Agenda and I click on the icon calendar, it will be redirected to juin 17 - 23 of the Planning. My code is : https://codesandbox.io/s/m7k904y3o8 I try to send the date with getWeek() , but it doesn't work. How can I fix it ? You can add additional data to this.props.history.push which will then be available in the location prop