I am trying this to get 2 values to be inserted in an js array.
$scope.ttabs = [];
for(p = 1; p <= $scope.no_of_groups; p++) {
$scope.ttabs[p] = [1];
console.log($scope.ttabs);
}
the p $scope.no_of_groups is here has value 2.
Now I am getting console output as ..
[undefined, [1], [1]]
why does it showing undefined at first index?
Because you start from the index 1. Array's index starts from the 0. In your code you don't assign any value to the index 0, so it will have the default value which is undefined.
Change you code into to start from the 0, and also remove the equal sign from the condition.
$scope.ttabs = [];
for(var p = 0; p < $scope.no_of_groups; p++) {
$scope.ttabs[p] = [1];
console.log($scope.ttabs);
}
console.log($scope.ttabs);
Output
[[1], [1]]
console.log($scope.ttabs); needs to be out of the for loop
{} object with the properties names in indexes, like a[1], a[2], but it is not a good practice l to use an object as an array. I think in your case you can manipulate with the array $scope.ttabs = [];
for(p = 0; p <= $scope.no_of_groups; p++) {
$scope.ttabs[p] = [1];
console.log($scope.ttabs);
}
Javascript array starts from 0th index so you are getting undefined for 1st place
Because you start p = 1, when you assign that as an index to the array, the array is allocated with length 2, since arrays are index from index 0. Since nothing is inserted into the array at index 0, that index is undefined.
var ar = [];
for(var i = 1;i < 2;i++){
ar[1] = 1;
}
console.log(ar) // outputs [undefined, 1, 1]
while:
var ar = [];
for(var i = 0;i < 2;i++){
ar[1] = 1;
}
console.log(ar) // outputs [1, 1]