variable-assignment

来源： https://stackoverflow.com/questions/63209322/why-is-let-allowed-as-a-variable-name

问题 I recently answered a question where a user was having trouble because they were appending a multi-dimensional array to another array, and it was brought to my attention in my answer that it is possible to use iterable unpacking to populate an x and y value and assign to board[x][y] on the same line. I had expected this to throw an error as x and y had at the time not been defined, as, even in the iterable-unpacking tag it reads: elements of an iterable are simultaneously assigned to multiple

问题 Working with Futures in Dart, I've come across an interesting issue. import 'dart:async'; class Egg { String style; Egg(this.style); } Future cookEggs(List<Egg> list) => new Future(() => ['omelette','over easy'].forEach((_) => list.add(new Egg(_))) ); Future cookOne(Egg egg) => new Future(() => egg = new Egg('scrambled')); void main() { List<Egg> eggList = new List(); Egg single; cookEggs(eggList).whenComplete(() => eggList.forEach((_) => print(_.style)); cookOne(single).whenComplete(() =>

问题 This question already has answers here : How do I correctly clone a JavaScript object? (68 answers) Closed 3 years ago . I am having a little problem assigning objects in javascript. take a look at this sample code that reproduces my problem. var fruit = { name: "Apple" }; var vegetable = fruit; vegetable.name = "potatoe"; console.log(fruit); it logs Object {name: "potatoe"} How can I assign the value not the reference of an object to another object? 回答1: You can use Object.assign: var fruit

问题 This question already has answers here : How do I correctly clone a JavaScript object? (68 answers) Closed 3 years ago . I am having a little problem assigning objects in javascript. take a look at this sample code that reproduces my problem. var fruit = { name: "Apple" }; var vegetable = fruit; vegetable.name = "potatoe"; console.log(fruit); it logs Object {name: "potatoe"} How can I assign the value not the reference of an object to another object? 回答1: You can use Object.assign: var fruit

问题 The increase assignment operator ( += ) is often used in [PowerShell] questions and answers at the StackOverflow site to construct a collection objects, e.g.: $Collection = @() 1..$Size | ForEach-Object { $Collection += [PSCustomObject]@{Index = $_; Name = "Name$_"} } Yet it appears an very inefficient operation. Is it Ok to generally state that the increase assignment operator ( += ) should be avoided for building an object collection in PowerShell? 回答1: Yes, the increase assignment operator

问题 Working with legacy code I came across some strange variable assignments that I am not sure are legal VB6 syntax, but I cannot find the documentation to back up the feeling. Dim ComStart, ComEnd, CR As Boolean ComStart = ComEnd = CR = False My suspicions are a) the original declarations should be Dim ComStart as Boolean, ComEnd as Boolean, CR as Boolean b) the declarations as they are implemented now will not assign anything to ComStart . Any answers or documentation are much appreciated 回答1:

问题 I want to do something to a couple of variables using operators in quick succession. I don't think what I want to do is important as such; my question is more about the fundamentals of JavaScript evaluation. In the three examples below, I try to use addition to change the values of two variables. However, not all perform as I (perhaps naïvely) expected. JSFiddle here. OPERATIONS AS THREE SEPARATE STATEMENTS var a = 9, b = 2; a += b; b += a; a += b; // a === 24, b === 13 OPERATIONS SEPARATED

问题 I want to do something to a couple of variables using operators in quick succession. I don't think what I want to do is important as such; my question is more about the fundamentals of JavaScript evaluation. In the three examples below, I try to use addition to change the values of two variables. However, not all perform as I (perhaps naïvely) expected. JSFiddle here. OPERATIONS AS THREE SEPARATE STATEMENTS var a = 9, b = 2; a += b; b += a; a += b; // a === 24, b === 13 OPERATIONS SEPARATED

问题 Im having trouble figuring out how to implement the equivalent of overloading the assignment operator in C++ to Java. I know there is no such thing, but I need to simulate it. I've tried overriding the Clone() function, but no luck. Any ideas? Below is my main Queue p = new Queue(); Queue q = new Queue(); p.enqueue('a'); p.enqueue(9); p.enqueue(10); p.enqueue(310); p.enqueue(8); q = p; System.out.print(p); And here is the clone function public void Clone(Queue other) throws Throwable { System