Problem arises with the for loop when trying to iterate through the final 5 objects in reverse sequence

Question

Problem arises with the for loop when trying to iterate through the final 5 objects in reverse sequence

I have a single JSON array that I would like to display on my user interface by only showing the last 5 JSON objects in reverse order. If the length of the array is less than 5, then all objects should be displayed in reverse order.

Currently, I can successfully display the last 5 objects if the length is greater than 5. However, if the array size is less than 5, my logic does not work as intended. Could someone assist me in fixing this issue?

for (var i = response.length - 1 ; i >= Math.max(response.length-5, 0) ; --i) {
        var date = new Date(response[i].transactiondate);
        var year = date.getFullYear();
        var month = date.getMonth() + 1;
        var dt = date.getDate();
        response[i].transactiondate = dt + '-' + month + '-' + year;
        outputdata += '<br>' + response[i].transactiondate + ' ' + response[i].amount + ' ' + response[i].description;
}

javascript arrays json

Answer 1

Answer №1

To improve your code, consider adding a condition for your case like this:
var start = (response.length >=5) ? response.length-5 : 0;

for (var i = response.length - 1 ; i >= start ; --i) {
        var date = new Date(response[i].transactiondate);
        var year = date.getFullYear();
        var month = date.getMonth() + 1;
        var dt = date.getDate();
        response[i].transactiondate = dt + '-' + month + '-' + year;
        outputdata += '<br>' + response[i].transactiondate + ' ' + response[i].amount + ' ' + response[i].description;
}

Answer 2

To improve your code, consider adding a condition for your case like this:
var start = (response.length >=5) ? response.length-5 : 0;

for (var i = response.length - 1 ; i >= start ; --i) {
        var date = new Date(response[i].transactiondate);
        var year = date.getFullYear();
        var month = date.getMonth() + 1;
        var dt = date.getDate();
        response[i].transactiondate = dt + '-' + month + '-' + year;
        outputdata += '<br>' + response[i].transactiondate + ' ' + response[i].amount + ' ' + response[i].description;
}

Answer 3

Answer №2

To determine if i is greater than or equal to zero, you could also use this approach.

for (var i = response.length - 1; i >= response.length - 5 && i >= 0; --i) {

Alternatively, you can set a variable for the lower limit.

var min = response.length > 5 ? response.length - 5 : 0;

for (var i = response.length - 1; i >= min; --i) {

Answer 4

To determine if i is greater than or equal to zero, you could also use this approach.

for (var i = response.length - 1; i >= response.length - 5 && i >= 0; --i) {

Alternatively, you can set a variable for the lower limit.

var min = response.length > 5 ? response.length - 5 : 0;

for (var i = response.length - 1; i >= min; --i) {

Answer 5

Answer №3

To achieve this, utilize the functions reverse() and splice()

result = result.reverse();
result = result.splice(5);

The updated response object will now contain the last five records in reversed order. Simply iterate through it as follows:

for (i = 0; i < result.length; i++) {
     //Your logic here
}

Answer 6

To achieve this, utilize the functions reverse() and splice()

result = result.reverse();
result = result.splice(5);

The updated response object will now contain the last five records in reversed order. Simply iterate through it as follows:

for (i = 0; i < result.length; i++) {
     //Your logic here
}

Answer 7

Answer №4

Below is a solution that involves updating the original array without altering it:

response = response.slice(-5).reverse();

for (var i = 0 ; i < response.length ; i++) {
var date = new Date(response[i].transactiondate);
        var year = date.getFullYear();
        var month = date.getMonth() + 1;
        var dt = date.getDate();
        response[i].transactiondate = dt + '-' + month + '-' + year;
        outputdata += '<br>' + response[i].transactiondate + '&nbsp;' + response[i].amount + '&nbsp;' + response[i].description;
}

Answer 8

Below is a solution that involves updating the original array without altering it:

response = response.slice(-5).reverse();

for (var i = 0 ; i < response.length ; i++) {
var date = new Date(response[i].transactiondate);
        var year = date.getFullYear();
        var month = date.getMonth() + 1;
        var dt = date.getDate();
        response[i].transactiondate = dt + '-' + month + '-' + year;
        outputdata += '<br>' + response[i].transactiondate + '&nbsp;' + response[i].amount + '&nbsp;' + response[i].description;
}

Problem arises with the for loop when trying to iterate through the final 5 objects in reverse sequence

Answer №1

Answer №2

Answer №3

Answer №4

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