Data push into array overwrites values

Question

I am trying to pass an array to a function and convert the numeric date.

E.g.: 2020-02-29 converted to 29th February 2020 (Saturday).

My code is below. When I am trying to push the converted date to array, the previous value get overwritten. I have gone through many articles on StackOverflow, but didn't find any best solution for it. I have created a new local array before pushing the same one (the same reference) each time, but the problem still persist.

Could you suggest me a better solution for my problem statement OR should I do some modification in the existing code?

Array data as input:

var data = ['2020-02-29', '2020-03-01', '2020-03-02'];

Start of a function:

function getFullName(data) {
    for(var i=0;i<data.length;i++){
        var d = new Date(data[i]);
        var date = d.getDate();
        var month = d.getMonth();
        var year = d.getFullYear();
        var dayName = d.toLocaleDateString('en-US', { weekday: 'long' });

        function ordinal_suffix_of(i) {
            var j = (i % 10);
            k = (i % 100);
            if (j == 1 && k != 11) {
                return i + "st";
            }
            if (j == 2 && k != 12) {
                return i + "nd";
            }
            if (j == 3 && k != 13) {
                return i + "rd";
            }
            return i + "th";
        }
        var pdate = ordinal_suffix_of(date);

        var monthNames = ["January", "February", "March", "April", "May", "June",
            "July", "August", "September", "October", "November", "December"
        ];
        var result = [];
        var pmonth = monthNames[month];
        var response = pdate + ' ' + pmonth + ' ' + year + ' (' + dayName + ')';
        result.push(response);
        console.log(result);
    }
     return result;
};

Calling function:

getFullName(data);

It is not the push who overwrites your data but it is response = because you store the variable response in your result array and you change the variable value also you write result = [] everytime you call the function which resets result — codeanjero
– codeanjero, Commented Mar 26, 2020 at 17:43

Anurag Srivastava · Accepted Answer · 2020-03-26 17:47:45Z

There is just a minor issue with the code, your result variable must be defined outside the loop:

// Array data as input

var data = ['2020-02-29', '2020-03-01', '2020-03-02'];

// Start of a function

function getFullName(data) {
    var result = []; // Define here
    for(var i=0;i<data.length;i++){
        var d = new Date(data[i]);
        var date = d.getDate();
        var month = d.getMonth();
        var year = d.getFullYear();
        var dayName = d.toLocaleDateString('en-US', { weekday: 'long' });

        function ordinal_suffix_of(i) {
            var j = (i % 10);
            k = (i % 100);
            if (j == 1 && k != 11) {
                return i + "st";
            }
            if (j == 2 && k != 12) {
                return i + "nd";
            }
            if (j == 3 && k != 13) {
                return i + "rd";
            }
            return i + "th";
        }
        var pdate = ordinal_suffix_of(date);

        var monthNames = ["January", "February", "March", "April", "May", "June",
            "July", "August", "September", "October", "November", "December"
        ];
        var pmonth = monthNames[month];
        var response = pdate + ' ' + pmonth + ' ' + year + ' (' + dayName + ')';
        result.push(response);
    }
     return result;
};

// Calling function 

console.log(getFullName(data));

ponury-kostek · Accepted Answer · 2020-03-26 17:47:36Z

0

Move your var result = []; declaration before for loop, because result is overwritten in every iteration

function broken() {
  for( var i = 0; i < 3; i++ ) {
    var result = [];
    result.push(i)
  }
  return result;
}

function fixed() {
  var result = [];
  for( var i = 0; i < 3; i++ ) {  
    result.push(i)
  }
  return result;
}


console.log(broken());
console.log(fixed());

answered Mar 26, 2020 at 17:47

ponury-kostek

8,0835 gold badges27 silver badges33 bronze badges

Comments

ThomasTaeChoi · Accepted Answer · 2020-03-26 17:48:29Z

0

Because you are initializing your var result = [] within the for(...){}, your result gets "wiped out" and creates a new array every iteration of your for loop

you can solve the problem by moving var result = [] to the outside of your getFullName function OR move it outside of for loop

p.s. This looks like you need to understand more about what lexical scope is in javascript. I suggest doing some research into the high-level concept of lexical scopes.

answered Mar 26, 2020 at 17:48

ThomasTaeChoi

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