将第一个数组的元素复制到第二个没有双重com的元素

Question

I've got some problems with these two arrays.

for (i = 0; i < post_data_route.length; i++) {
    route_array.push(coordinates_array[post_data_route[i] - 1]);
}
route_array[route_array.length - 1][0] -= 0.00001;
route_array[route_array.length - 1][1] -= 0.00001;

route_array[route_array.length - 1] equals route_array[0] but when I try to change one of them second one changes too. I guess that's about the pointer but why does it happen? Isn't it just pushing values of array to another one? How could I get rid of it? Thanks for your answers and suggestions.

Answer 1

You are pushing not the values, but another array, because your array is multidimensional. You need to push the value of each dimensions separately.

Example:

route_array.push([
      coordinates_array[post_data_route[i] - 1][0],
      coordinates_array[post_data_route[i] - 1][1]
      ]);

Answer 2

You could use Array#slice for the data, that means, you get a copy.

The slice() method returns a shallow copy of a portion of an array into a new array object selected from begin to end (end not included). The original array will not be modified.

for (i = 0; i < post_data_route.length; i++) {
    route_array.push(coordinates_array[post_data_route[i] - 1].slice());
}

Answer 3

you can create new objects and arrays with JSON.parse(JSON.stringify(yourArray))

its not so nice but its working