如何在 Javascript 中实现三元赋值？

Question

I would like to do a reassignment of a class variable in Javascript (or Typescript) using a ternary operator. The reassignment of this.foo depends on the current value of this.foo which I can update with the following:

setFoo = () => {
    this.foo = this.foo ? "" : "foo";
}

However, I am wondering if I can do reassignment of this.foo without writing this.foo twice. This would be helpful because I am trying to dynamically update classes on an Angular component (written in Typescript).

I would like to be able to write something like the following which makes use of truthy/falsy values. If this.foo is truthy, then "" is assigned; otherwise, "foo" is assigned:

setFoo = () => {
    this.foo =? "" : "foo";
}

I have tried searching for similar questions but could not find an answer. My initial thought was to use the ??= operator in Typescript 4.0 but I do not think it will work. Perhaps my ideal solution does not exist because it could be a bad programming habit. Thanks

Answer 1

Great question. Unfortunately this is not possible . There is a shorthand version that some people use, but it still includes a duplication:

foo = foo || otherCondition;

So the shorthand of a shorthand, not too useful in my opinion.

Short answer : I'd go with the normal ternary.

Answer 2

您必须使用 IF ELSE 而不是使用三元语句，if else 将使您更好地控制在它下编写的语句并且使用效率更高。