如何从数组中获取具有最大属性的对象？

Question

I have an array of objects, with each object containing other 'subobjects'. I need to return the subobject with the largest 'quality' property.

The code below logs out all subobjects. How do I only return the one with the largest quality?

 var maxQuality = function(Arr) { Arr.forEach(function(obj, index) { Math.max.apply(Math, obj.products.map(function(subObj) { console.log(subObj); })) }); }, store = [ { products: [ { quality: 1, info: 'info 1' }, { quality: 2, info: 'info 2' }, { quality: 3, info: 'info 3' } ] } ], maxQualityProduct = maxQuality(store); 

Answer 1

You can do that using the reduce() method on the array

 var products = [ { quality: 1, info: 'info 1' }, { quality: 2, info: 'info 2' }, { quality: 3, info: 'info 3' } ]; var highest = products.reduce(function(prev, current) { return prev.quality > current.quality ? prev : current }, {}); console.log(highest); 

Note that reduce takes two parameters - one is the callback and the second is the initial item that you start with called seed . In this case, since we are only checking a flat value, a seed of an empty object will work fine since when the property quality is taken from it it would return undefined and that would be less than any of the other products. However, for more complex structures or comparisons, you might need to give an actual item from the array as a seed.

Answer 2

Although the other .reduce answer probably gives you what you need, if the store array were to contain more than one object - not sure if that is something you will want/need - you could use this:

var maxQuality = function(storeArray) {
    function highestQuality(prev, curr) {
        return prev.quality > curr.quality ? prev : curr
    }

    return storeArray.map(function(obj) {
      return obj.products.reduce(highestQuality)
    }).reduce(highestQuality);
}

Answer 3

我想这可以归结为一个简单的Array.prototype.sort类的东西：

products.sort(( a, b ) => b.quality - a.quality )[ 0 ];

Answer 4

You can use following snippet:

 var maxQuality = function(Arr) { var result = undefined; for (var obj of store) { for (var product of obj.products) { if (!result || product.quality > result.quality) { result = product; } } } return result; }, store = [ { products: [ { quality: 1, info: 'info 1' }, { quality: 2, info: 'info 2' }, { quality: 3, info: 'info 3' } ] } ], maxQualityProduct = maxQuality(store); console.log(maxQualityProduct);