state

问题 I am trying to change the value of a hidden input field, depending on the value of a checkbox. I don't know much about Javascript but this is what I have so far. <input type="hidden" value="" id="delterms" name="O_" /> <input type="checkbox" id="checkbox" onchange="terms()" /> <script type="text/javascript"> var checked = document.getElementById('checkbox').checked; function terms() { if (checked==false) { document.getElementById('delterms').value='' } else { document.getElementById('delterms

问题 I have a prop called friends which is being listed as a checkboxes (default: unselected). Example output: o Bob Smith o Tom Brown How can I save the id's of all the names that are selected? E.g. both are ticked/selected -> ids 1 and 2 is stored. This is what I have so far: class SelectFriends extends Component { constructor(props) { super(props) this.state = { SelectedFriendsIds: [], } } render() { const { SelectedFriendsIds } = this.state const { userId, friends, addFriendsTo } = this.props

问题 My company has a 3rd party web service we are designing a front end for. The "objects" used by this web service are very large (and variable depending on the number of sub-entities created). The web service does not expose methods to commit/load sub-entities, only the full object hierarchy. The UI itself is split into many sub screens, and master/detail views to be able to efficiently/easily edit the large amount of data. The issue is where to store all the data you aren't currently looking

问题 I need to check that a user have logged in and been authenticated before letting my him or her use my backbone.js -based application. The user authentication is stored in a native backbone model as a property, which I check before starting my main router by invoking Backbone.history.start . This way - an unauthenticated user is sent to the login page directly. Is this sufficient? if (!myApp.state.loggedIn) { window.location.hash = "login"; // Set url to #login } Backbone.history.start(); //

问题 I've got one long GridView control on ma website. It allows row selection. The problem is, when I scroll down this GridView and select some of the bottom rows the selection occurs, but whole GridView is scrolling back to top. Does enyone know how to avoid this? 回答1: If it's happening during a postback, then in your <%@ Page %> directive you can add the following: MaintainScrollPositionOnPostback="true" This was added in .NET 2.0, and adds some JavaScript to the page to ensure that the page

问题 We're using Angular-ui-router for our app state management. A problem we're having is that every component refreshes when the $state changes, even if it's a variable that is updated that does not exist/not used in some components. For example, we have a TickersPanel and a TagsPanel. When a Ticker is selected, the TagsPanel should be updated and refreshed, however when a tag is selected in the TagsPanel, the TickersPanel should NOT refresh, but it currently does. I found out that { notify:

问题 In the state pattern how is this modeled ? state A to state B on trigger X and conditon C1 when current state is A state A to state C on trigger X and condition C2 when current state is A how is this usually accomplished ? I have a lot of guard conditions that I may need to implement. 回答1: That's pretty standard see e.g. this example. [Edited on basis it's not homework!] Assuming I understand right: You have one event ( X ) which can trigger one of two possible transitions Selecting which

问题 Is there a consensus on how to avoid memoization causing bugs due to mutable state? In this example, a cached result had its state mutated, and therefore gave the wrong result the second time it was called. class Greeter def initialize @greeting_cache = {} end def expensive_greeting_calculation(formality) case formality when :casual then "Hi" when :formal then "Hello" end end def greeting(formality) unless @greeting_cache.has_key?(formality) @greeting_cache[formality] = expensive_greeting

问题 I am getting a 'session state not available in this context' error. The error is nested in the sender parameter of a number of methods within the Global.asax file: Application_BeginRequest Application_AuthenticateRequest Session_Start Application_Error The error happens on the very first page load (and all page loads thereafter). I've added a completely new and empty page, WebForm1.aspx, to the project and made it my start page. You'd think nothing could go wrong on an empty page . No code of

问题 enum SectionType: String, CaseIterable { case top = "Top" case best = "Best" } struct ContentView : View { @State private var selection: Int = 0 var body: some View { SegmentedControl(selection: $selection) { ForEach(SectionType.allCases.identified(by: \.self)) { type in Text(type.rawValue).tag(type) } } } } How do I run code (e.g print("Selection changed to \(selection)") when the $selection state changes? I looked through the docs and I couldn't find anything. 回答1: You can't use didSet