Finding the max value of an attribute in an array of objects

Question

I'm looking for a really quick, clean and efficient way to get the max "y" value in the following JSON slice:

[   {     "x": "8/11/2009",     "y": 0.026572007   },   {     "x": "8/12/2009",     "y": 0.025057454   },   {     "x": "8/13/2009",     "y": 0.024530916   },   {     "x": "8/14/2009",     "y": 0.031004457   } ] 

Is a for-loop the only way to go about it? I'm keen on somehow using Math.max.

Answer 1

To find the maximum y value of the objects in array:

Math.max.apply(Math, array.map(function(o) { return o.y; })) 

Answer 2

Find the object whose property "Y" has the greatest value in an array of objects

One way would be to use Array reduce..

const max = data.reduce(function(prev, current) {     return (prev.y > current.y) ? prev : current }) //returns object 

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/Reduce http://caniuse.com/#search=reduce (IE9 and above)

If you don't need to support IE (only Edge), or can use a pre-compiler such as Babel you could use the more terse syntax.

const max = data.reduce((prev, current) => (prev.y > current.y) ? prev : current)