The loop outcome is not determined

Question

The loop outcome is not determined

Storing function arguments in a specific format

["2015-07-05 00:30", 59]
...
["2015-07-05 01:00", 62]

function generateCSV(timeAndValue) {
    object = {}
    var zero = 0;
    for(i = 0; i < timeAndValue.length; i++){
        var value = timeAndValue[i]
        var days = moment(value[0]).format('YYYY-MM-DD');
        obj[days] += value[1] + ', '
    }
}

It assigns the days and total values spent on each day while looping. 2015-07-05:

"2015-07-05: "undefined59, 62, 65...

2015-07-06: "undefined61, 61, 60..."

Each parameter starting with "undefined". How can I prevent this?

javascript

Answer 1

Answer №1

Revise

obj[days] += value[1] + ', '

Replace it with

if (obj[days]===undefined) obj[days] = ''; 
obj[days] += value[1] + ', '

This change prevents adding a string to undefined.

Instead of appending ", " after each value, consider creating an array within your loop:

if (obj[days]===undefined) obj[days] = []; 
obj[days].push(value[1])

Later, use join to avoid the trailing comma and defer string manipulation until rendering.

Double-check variable declarations: object might be fine if defined in an outer scope, but beware of undeclared variables like i, which could cause issues if used elsewhere in your codebase.

Edit: A typo was pointed out by James - it should either be "object" or "obj".

Answer 2

Revise

obj[days] += value[1] + ', '

Replace it with

if (obj[days]===undefined) obj[days] = ''; 
obj[days] += value[1] + ', '

This change prevents adding a string to undefined.

Instead of appending ", " after each value, consider creating an array within your loop:

if (obj[days]===undefined) obj[days] = []; 
obj[days].push(value[1])

Later, use join to avoid the trailing comma and defer string manipulation until rendering.

Double-check variable declarations: object might be fine if defined in an outer scope, but beware of undeclared variables like i, which could cause issues if used elsewhere in your codebase.

Edit: A typo was pointed out by James - it should either be "object" or "obj".

The loop outcome is not determined

Answer №1

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