function arrayToList(array) {
var list = null
for (var i = 0; i < array.length; i++)
list = {value: array[i], rest: list};
return list;
}
console.log(arrayToList([10, 20, 30]));
// {value: 30, rest:{ value:20, rest:{value: 10, rest: null}}
I've looked at this function from eloquent javascript exercise for hours, and can't get it why the result are reversed. Any help would be appreciated.
Here's what's happening when you are iterating in your for-loop:
First iteration:
i = 0;
list = {value:10, rest:null}
Second iteration:
i = 1;
list = {value:20, rest:{value:10, rest: null}}
Third iteration:
i = 2;
list = {value:30, rest:{value:20, rest:{value:10, rest: null}}}
On each iteration, you are nesting your list object within itself:
list = {value: array[i], rest: list};
Set an output in the loop, than you can see how it works:
function arrayToList(array) {
var list = null
for(var i = 0; i < array.length; i++) {
list = {value: array[i], rest: list};
console.log(list);
console.log('\n');
}
return list;
}
arrayToList([10, 20, 30]);
/* Output
{ value: 10, rest: null }
{ value: 20, rest: { value: 10, rest: null } }
{ value: 30, rest: { value: 20, rest: { value: 10, rest: null } } }
*/
You have set list = null.
The first time in the loop, list is "{ value: 10, rest: null }"
-> "null" nested within.
The second time in the loop, list is "{ value: 20, rest: { value: 10, rest: null } }"
-> "{ value: 10, rest: null }" nested within.
For the last time, list is "{ value: 30, rest: { value: 20, rest: { value: 10, rest: null } } }"
-> "{ value: 20, rest: { value: 10, rest: null } }" nested within.
arrayToList()function?