I need to sum all of the values of a key "number" from several objects within an array. What would be the correct way to do this? This is what I've tried.
var numarray = [{"number":"10"},{"number":"2"},{"number":"5"},
{"number":"3"},{"number":"21"},{"number":"43"},{"number":"30"}];
function Sum() {
var sum;
for (number in numarray[i]){
alert(sum); //sum would be the result I need to get
}
}
Use forEach to loop through each of the json object.
Use parseInt to convert the values to integer
var numarray = [
{"number":"10"},
{"number":"2"},
{"number":"5"},
{"number":"3"},
{"number":"21"},
{"number":"43"},
{"number":"30"}];
function Sum(){
var sum=0;
numarray.forEach(function(item){
sum += parseInt(item.number)
})
document.write('<pre>'+sum+'</pre>')
}
Sum()
EDIT
When using parseInt it is better to specify the radix
parseInt(item.number,10)
Using a 10 radix means the number is parsed with a base 10 and thus turns the number into the integer .If parseInt detects a leading zero it will parse the number in octal base
Using Number
Number(item.number)
It will not detect any any octal
item in this case? the value of the object?
parseInt.
parseInt instead of Number?You can use reduce for this:
Here's how you would normally find the sum of elements in an array:
var sum = arr.reduce(function(a,b) {
return a + b;
});
Since you have an array of objects, you'll need to change this to something like:
var sum = arr.reduce(function(a,b) {
return parseFloat(a) + parseFloat(b.number);
}, 0);
Notice the 0 I've added added as a parameter? It's the default parameter and required in this case.
[javascript] sum properties) before you ask a new question. There are quite a few similar questions which could help you.