从对象数组中的对象属性返回最大数字

Question

I want to extract data from an Object inside an Array of Objects. This is how it looks now:

Object
 0: Object
     id: "e0"
     score: 0
 1: Object
     id: "e1"
     score: 1
 2: Object
     id: "e2"
     score: 2
 3: Object
     id: "e3"
     score: "-"
 4: Object
     id: "e4"
     score: "-"

Question:
How can I get the highest score value (2) and save it to a variable? Please not that there are also "-".

Answer 1

That example is no such thing as an array of objects in JavaScript. What you are showing is an object which uses numbers as keys. If what you want is to retrieve the highest score value from the object you show, you can iterate through enumerable properties of an object with a for..in construct.

So you'll have to iterate through the object, comparing the current score you're checking with the maximum value stored:

var max = 0;
for (var key in obj) {
    if (obj[key].score && typeof obj[key].score === 'number' && obj[key].score > max) {
        max = obj[key].score;
    }
}

Answer 2

You can work over the array doing something like this:

var scores = [
  { id: 'e0', score: '2' },
  { id: 'e1', score: '0' },
  { id: 'e2', score: '-' },
  { id: 'e3', score: '1' }
];

scores
  .map(obj => parseInt(obj.score))                 // Transform each score to Integers
  .filter(val => !isNaN(val))                      // Filter the "Non Integer" values
  .reduce((acc, val) => Math.max(acc, val), -1);   // Find the highest value

Answer 3

You can loop through the array, and store the score if it is bigger than the values you've encountered before:

 var items = [{id: "e0", score: 0 }, {id: "e1", score: 1 }, {id: "e2", score: 2}, {id: "e3", score: "-"}, {id: "e4", score: "-"}]; var max_score = 0; for(var i=0; i<items.length; i++) { // isNaN will tell you if the value is Not a Number if(!isNaN(items[i].score) && items[i].score > max_score) { max_score = items[i].score; } } alert('The highest score is ' + max_score + '.'); 

Answer 4

You may use Reduce :

 var items = [{id: "e0", score: '-' }, {id: "e1", score: 1 }, {id: "e2", score: 2}, {id: "e3", score: "-"}, {id: "e4", score: "-"}]; var max_score = items.reduce(function(previousValue, currentValue, currentIndex, arr) { if (isNaN(previousValue.score)) { return currentValue; } if (isNaN(currentValue.score)) { return previousValue; } return (currentValue.score > previousValue.score) ? currentValue : previousValue; }).score; document.write('Reuslt = ' + max_score);