Created
May 12, 2016 13:40
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Using Array.reduce to sum a property in an array of objects
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var accounts = [ | |
{ name: 'James Brown', msgCount: 123 }, | |
{ name: 'Stevie Wonder', msgCount: 22 }, | |
{ name: 'Sly Stone', msgCount: 16 }, | |
{ name: 'Otis Redding', msgCount: 300 } // Otis has the most messages | |
]; | |
// get sum of msgCount prop across all objects in array | |
var msgTotal = accounts.reduce(function(prev, cur) { | |
return prev + cur.msgCount; | |
}, 0); | |
console.log('Total Messages:', msgTotal); // Total Messages: 461 |
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simplify it as total = sum_all_items(amount * (1 - discount))
OR
first, just make, discount = 1 - discount, and then, sum(amount * discount)