how to create a javascript Set with objects?

Like the first comment by Pointy says, objects are only equal to each other in JavaScript if they refer to the same place in memory. For example,

const object1 = { foo: 'bar' };
const object2 = object1;

object1 === object2 //true;
{ foo: 'bar' } === { foo: 'bar' } //false

There isn't any way around it with Set. One thing I've done in a similar situation is loop through the array and create a dictionary (either with a JavaScript Object or Map), generating a unique key for each item, then iterating through that Object or Map to get the unique times.

For example, in your case, something like:

const availableTimesMap = availableTimes.reduce((acc, timeObject) => {
  const key = `${timeObject.type}-${timeObject.time}`;
  acc[key] = timeObject;
}, {});

const uniqueTimes = Object.values(availableTimesMap);

Hope this helps. Let me know if you have any questions.

I had a similar issue in my own project. To solve it I ended up having to use strings to be the keys of a Map object. You would need to figure out a standard way to ID a time so that two "identical" times are converted to identical strings. Simply using the time would probably work well enough.

const timesAvailable = new Map()
businessList.forEach(item =>
    item.availableTimes.forEach(item =>
        timesAvailable.add(item.time, item)
    )
)

Alternatively, you could do away with objects and just use the string times.

[
    {"availableTimes": ["06:30", "07:00"]},
    {"availableTimes": ["08:30", "07:00"]}
]

I am not sure what the structure of the result you want to get. I assume that if you want to get a set of non-duplicate objects and each object looks like this: {"type": "time", "time": "06:30"}.

let businessList = [
    {"availableTimes": [{"type": "time", "time": "06:30"}, {"type": "time", "time": "07:00"}]},

    {"availableTimes": [{"type": "time", "time": "08:30"}, {"type": "time", "time": "07:00"}]}
]
const timesAvailable = new Set(); // a set of strings representing time, which is used for checking duplicates
const availableBusiness = new Set(); //the result we want 

for(let business of businessList) {
    for (let availableTime of business.availableTimes) {
        if(availableTime.type === "time") {
            if(!timesAvailable.has(availableTime.time)){
                timesAvailable.add(availableTime.time);
                availableBusiness.add(availableTime);
            } 
        }
    }
}
console.log(availableBusiness);
console.log(timesAvailable);