• activ8r@sh.itjust.works
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    1 year ago

    In JS a Boolean has 4 states.
    true
    false
    undefined (where the key is set to undefined)
    undefined (where the key doesn’t exist on the object)

    if (obj.value === true) {  
        console.log(1);
    } else if (obj.value === false) {
        console.log(2);
    } else if ("value" in obj) { // key "value" is in the obj, but it is set to undefined 
        console.log(3);
    } else { // key "value" is not in object
        console.log(4);
    }
    

    You’re welcome.