Conditionally set an object property

Solution 1:

Use the spread operator.

data: {
    userId: 7,
    actionId: 36,
    ...myCondition && {express: true}
}

Note that if you're using Flow, that syntax might generate type check errors. You can write the above more explicitly, and less succinctly, as:

data: {
    userId: 7,
    actionId: 36,
    ...(myCondition ? {express: true} : {})
}

Solution 2:

Do it like this :

data: {
    userId: 7,
    actionId: 36,
    express: (myCondition ? true : undefined)
}

A property whose value is undefined isn't written when you stringify the object to JSON.

EDIT : It appears from the comments that there is no JSON involved in fact. OP is using $.ajax so $.param is probably used. $.param, unfortunately, does create an entry for properties whose value is undefined. So there's probably no solution without any supplementary line of code.

Solution 3:

You can do it if you define your object using an anonymous function instead of object literal notation:

var data = new function(){
    this.userId = 7;
    this.actionId = 36;
    myCondition && (this.express = true);
};

The resulting data object is the exact same, except it's constructor will be the anonymous function instead of window.Object.

Solution 4:

You could do something like this:

var json = JSON.stringify( {
    data: {
        userId: 7,
        actionId: 36,
        express: (myCondition ? true : null)
    }
});

Solution 5:

A bit old but there is a good solution as well you can do :

data: {
    userId: 7,
    actionId: 36
}

Object.assign(data, !myCondition && { express: yourValue });

Thus it will assign your express property with the value you need if your condition is false.