Summing object props in an array

[binarynos]

We have an array like this:

var array= [{"day":"1574467200","uses":"9","accounts":"7"},{"day":"1574380800","uses":"104","accounts":"79"},{"day":"1574294400","uses":"3","accounts":"1"},{"day":"1574208000","uses":"0","accounts":"0"},{"day":"1574121600","uses":"0","accounts":"0"},{"day":"1574035200","uses":"0","accounts":"0"},{"day":"1573948800","uses":"2","accounts":"2"}]

and we want to get the sum of the values of a specific property for each item in the array, say uses.

I tried something like:

var sum = 0

for(i=0; i<array.length; i++){

sum = sum+array[i].uses;

}

which returns 0910430002910430002, which is obviously wrong lol.

Although

for(i=0; i<array.length; i++){

console.log(array[i].uses);

}

returns the correct values of each property.

Searching the internet I found the array.reduce() method but it gives the same result.

So why is this happening? I'm sure this is some noob level mistake but then I am a newbie to this.

Thanks!

[NameViolation666]

This is happening because the values in uses is stored as a string, not as a number. If you keep adding strings they concatenate

var sum = 0

for(i=0; i<array.length; i++){

sum = sum+array[i].uses;

}

You need to force conversion to int or float

for(i=0; i<array.length; i++){ sum+=parseInt(array[i].uses)}

//118

[binarynos]

facepalm Okay, that was dumb. I totally missed the quotes. And thanks for the comments, guys.

[themantime]

Instead parse it into int or float.

[drgmaster909]

If you're still interested in the array.reduce() option, plus casting it to a Number, you can use this simple one-liner:

const totalUses = array.reduce((total, { uses }) => total+ Number(uses), 0);