Is there a way to only add a property if it is defined via the spread operator?-CodePudding

I have a variable name and I want to add it to an object only if it's defined and not null. For example, I check the value of name:

let name = null;
if(nameExists) {
    name = 'John Smith';
}

Then I only want to add it to the object as a field if it exists and is not null.

const results = {
   title: $(el).find('.title').text(), 
   name
};

But this doesn't work. Any ideas?

CodePudding user response：

I hope this example clears your concept.

function addName(name) {
    let obj = {"site":"stackoverflow"}; // create an object)=(it may be pre-existing)
    if(name) {
        obj = {...obj, name}; // add name field to obj only if it exists
    }
    return obj;
}

const ex1 = addName();
const ex2 = addName('John Smith');
console.log('If name is null: ', ex1);
console.log('If name exists: ', ex2);

CodePudding user response：

Well, to do that, you have to spread an object containing the property or an empty object, depending on whether you want to add the property:

const results = {
   title: $(el).find('.title').text(), 
   ...(
     name !== null
       ? {name}
       : {}
   )
};

But I think a conditional assignment could be clearer:

const results = {
   title: $(el).find('.title').text()
};

if(name !== null)
  results.name = name