When you return nothing from the reduce function it returns undefined and undefined + 1 === NaN. You should instead filter the array before reducing. records.filter(({gender}) => gender === ‘BOYS’) .reduce((sum, record) => sum + record.value)
lazy vars are only calculated once, the first time you use them. After that, they’re just like a normal variable. This is easy to test in a playground: class LazyExample { var firstName = “John” var lastName = “Smith” lazy var lazyFullName : String = { [unowned self] in return “\(self.firstName) \(self.lastName)” }() } let … Read more
Here is an approach I prefer with computed property & binding “on-the-fly” private var bindableIsVisibleError: Binding<Bool> { Binding ( get: { self.model.usernameResult.isVisibleError }, set: { if !$0 { self.model.dismissUsernameResultError() } } ) } and usage (as specified) Toggle(isOn: bindableIsVisibleError, label: { EmptyView() })
Your code should work if you setup everything correctly: http://codepen.io/CodinCat/pen/RKZeZe?editors=1010 A very common mistake is that you didn’t give your state initial data. You should declare the state shape explicitly, so instead of state: {} // or state: { nav: {} } do this: state: { nav: { type: ‘…’ }, … } or the … Read more
You can access computed properties like a property, not like a method: // correct console.log(this.myProperty); // wrong console.log(this.myProperty()); Note: If you treat it as a method with paracentesis () it shall throw an error like this Error in v-on handler: “TypeError: this.myProperty is not a function”.
Yes, you can setup watcher on computed property, see the fiddle. Following is the code to set watch on computed property: const demo = new Vue({ el: ‘#demo’, data() { return { age: ” }; }, computed: { doubleAge() { return 2 * this.age; } }, watch: { doubleAge(newValue) { alert(`yes, computed property changed: ${newValue}`); … Read more
In short, the first is a stored property that is initialized via a closure, with that closure being called only one time, when it is initialized. The second is a computed property whose get block is called every time you reference that property. The stored property’s initialization closure is called once and only once, but … Read more
Context YAML version 1.2 user wishes to include variable placeholders in YAML have placeholders replaced with computed values, upon yaml.load be able to use placeholders for both YAML mapping keys and values Problem YAML does not natively support variable placeholders. Anchors and Aliases almost provide the desired functionality, but these do not work as variable … Read more
You can’t create a computed property for each iteration. Ideally, each of those items would be their own component so each one can have its own fullName computed property. What you can do, if you don’t want to create a user component, is use a method instead. You can move fullName right from the computed … Read more
If you’re going to v-model a computed, it needs a setter. Whatever you want it to do with the updated value (probably write it to the $store, considering that’s what your getter pulls it from) you do in the setter. If writing it back to the store happens via form submission, you don’t want to … Read more