check large number from right side in array in Javascript

Also add dynamic key into Object

var arr = [1,2,25,46,6]
var newArr = [];
for(var i=0; i<arr.length; i++){
	var myObj = {}
	if(arr[i] < arr[i+1]){
		myObj[arr[i]] = arr[i+1]
		newArr.push(myObj);
    } else {
		myObj[arr[i]] = -1
		newArr.push(myObj);
    }
}

var newArr = [];
for(var i=0; i<arr.length; i++){
	if(arr[i] < arr[i+1]){
		newArr.push({[arr[i]] : arr[i+1]});
    } else {
		newArr.push({[arr[i]] : -1});
    }
}