如果未找到，则 JS 中的条件链接为 false

Question

In JS's optional chaining (I don't think it's implemented in current versions), can I have it evaluate to false if not found?

var obj = {a: {foo: "bar"}}
console.log(obj.a?.foo); //bar
console.log(obj.b?.foo); //this is undefined, I want it to be false

I read Optional Chaining in JavaScript and Null-safe property access (and conditional assignment) in ES6/2015 but neither answered my question.

Answer 1

You can use !! or != null (pay attention != not !== to check both undefined and null)

 var obj = {a: {foo: "bar"}}; console.log(!!obj.b?.foo); console.log(obj.b?.foo != null);