Initialise an object with array properties

How can I initialise an object in JavaScript, the properties of which would be arrays? I want to have an object of this format: My usecase is the following: – When a property does not exist, create this property which should be an array and add a number. – When a property exists already, push the number to that array; this way I cannot initialise an array every time. What I’ve done so far is this: I am getting this error: Uncaught TypeError: Cannot read property ‘push’ of undefined which makes sense, as the property has not been initialised as

How to initialise array in react-native using es6?

I am trying to create empty array in react-native using es6. But while accessing it I get an error data not defined. Here is the code snippet which I am using to initialise the array. constructor() {…