Javascript array push only if value not null

Question

I'm wondering if, and if how the following thing is working:

I have an array defined like the following:

var array = [
  {number: '1', value: 'one', context: 'someContext'}, 
  {number: '2', value: 'two', context: 'anotherContext'},
  ...
]

What I'm currently doing is pushing the elements into the array, so array.push({number: '1', value: 'one', context: 'someContext'}); and so on, with every array element.

Now this thing is extended: Say there's another key called 'content'. This key has a appropriate value, that is either undefined or a string. Now the question is: If I put the pushing in a function like this:

push(number, value, context, content) {
    array.push({
       number: number,
       value: value,
       context: context,
       content: content
    })
}

Is there anyway, I can make sure, that the key content is only added to the element, if the content (the function gets as parameter) is not null.

Of course I can modify function like that:

push(number, value, context, content) {
    if(!content) {
        array.push({
           number: number,
           value: value,
           context: context,
           content: content
       })
    } else {
        array.push({
           number: number,
           value: value,
           context: context
        })
   }
}

But the question is, if there is anyway to do this in the push function. I also thought about something like

array.push({
  number: number,
  value: value,
  context: context,
  content? content: content
})

So it would only be inserted if content is defined, but does this work, it didn't seem like, but maybe theres a mistake in my code.

Answer 1

If the objective isn't just to make code shorter, the most readable would be something like this, where you create the object, add the property if there is a value, and then push the object to the array.

push(number, value, context, content) {

    var o = {
        number  : number,
        value   : value,
        context : context
    }

    if (content !== null) o.content = content;

    array.push(o);
);

Here's an ES6 way to construct the object directly inside Array.push, and filter any that has null as a value.

function push(...arg) {
    array.push(['number','value','context','content'].reduce((a,b,i)=> {
        if (arg[i] !== null) a[b]=arg[i]; return a;
    }, {}))
}

Answer 2

With Spread operator for object literals (ECMAScript 2018) it looks super easy:

const myPush = (number, value, context, content) =>
  array.push({
    ...{ number, value, context },
    ...content && { content }
  });

Answer 3

If you are open to using ES2015, this can be done with Object.assign:

array.push(
  Object.assign(
    { number, value, context },
    content ? { content } : null
  )
);

Answer 4

It can be done by extending array:

//create Your own array object
myArray=function(){};
myArray.prototype=Object.create(Array.prototype);

//create method
myArray.prototype.pushDefined=function(obj){

  var newObj={};//create clean object 
  for (var key in obj){
  
    if (typeof obj[key]!='undefined' && obj[key]!=null){
      
      //this element is defined and is not null
      newObj[key]=obj[key];
      
    }
  }
  
  this.push(newObj);//push clean object without undefind properties

};

//tests
var arr=new myArray();
arr.pushDefined({ name:"John",surname:null});

console.log(arr[0]);

Or add this method to Array prototype:

Array.prototype.pushDefined=function(obj)... //this will be method in every array

I would not recommend changing original push method in Array because always think about other programmers who are using Array in this particular project.