Array Behaviour in Javascript
This is because chrome puts the value of the variable assignment in the console, when you initialize / declare a variable. This is an expected behavior.
Arrays are objects in JavaScript. Hence, arr[0] assignment after console.log assigning the array on the same reference where first var arr = [[2,2]]; refer. Both arr variables refer to the same single object.
It happens only with objects but not with Primitive values like numbers.
Example with primitive value
var arr = 1;console.log('Array is',arr); // 1arr++;console.log('Array is',arr); // 2Example with objects :
var arr = [[2,2]];console.log('Array is',arr);arr[0] = [3,3]To avoid that you can use this :
var arr = [[2,2]];console.log('Array is', JSON.parse(JSON.stringify(arr)));arr[0] = [3,3]