JavaScript。 如何通过数组函数更改对象中的某些数据？

Question

Maybe somebody knows how to change some data in an object via a function for an array?

For example, I have an object:

var nodes = [
  { topic: "Games",    topicscore: 100},
  { topic: "Fun",      topicscore: 550},
  { topic: "New York", topicscore: 7799},
  { topic: "Hillary",  topicscore: 745},
  { topic: "Politics", topicscore: 512},
  { topic: "Trump",    topicscore: 71}
];

And I have a function:

var filterScoreValues = function(array_input){
  var a_out = [];
  array_input.forEach(function(x){
    a_out.push(Math.ceil(x / Math.max.apply(null,array_input) * 10) + 5)
  });
  return a_out;
};

How I can apply this algorithm to topicscore of my object?

I wrote this, but I want a "pretty" variant, maybe via lodash or similar:

function filterScoreValues(input){
  var array = input.map(function (i) {
    return i.topicscore;
  });

  array.forEach(function(x, index){
    input[index]['topicscore'] = Math.ceil(x / Math.max.apply(null, array) * 10) + 5;
  });

  return input;
 };

I often used loops on my variant.. :(

Answer 1

how to change some data in an object via a function

Use the following optimized approach( without a function. It may be wrapped into function if there would be a need to call such function multiple times ):

 var nodes = [ { topic: "Games", topicscore: 100}, { topic: "Fun", topicscore: 550}, { topic: "New York", topicscore: 7799}, { topic: "Hillary", topicscore: 745}, { topic: "Politics", topicscore: 512}, { topic: "Trump", topicscore: 71} ]; // taking max 'topicscore' at once var max_score = Math.max.apply(null, nodes.map(function (o) { return o.topicscore; })); // processing each 'topicscore' item in place(without creating temporary arrays) nodes.forEach(function (o) { o.topicscore = Math.ceil(o.topicscore / max_score * 10) + 5; }); console.log(nodes); 

Answer 2

Use Array#map to extract the topicscore to an array. Calculate the max once using the topicscores array. Then Array#map the topicscores array into a normalized array using max .

 var nodes = [ { topic: "Games", topicscore: 100}, { topic: "Fun", topicscore: 550}, { topic: "New York", topicscore: 7799}, { topic: "Hillary", topicscore: 745}, { topic: "Politics", topicscore: 512}, { topic: "Trump", topicscore: 71} ]; function filterScoreValues(input){ var topicscores = input.map(function (i) { return i.topicscore; }); // extract the topicscores to array var max = Math.max.apply(null, topicscores); // calc the max return topicscores.map(function (score) { // map normalize and return the new array return Math.ceil(score / max * 10) + 5; }); }; var result = filterScoreValues(nodes); console.log(result); 

Answer 3

只需使用javascript：

filterScoreValues(nodes.map(node => node.topicscore));

Answer 4

Another alternative is:

var nodes = [
  { topic: "Games",    topicscore: 100},
  { topic: "Fun",      topicscore: 550},
  { topic: "New York", topicscore: 7799},
  { topic: "Hillary",  topicscore: 745},
  { topic: "Politics", topicscore: 512},
  { topic: "Trump",    topicscore: 71}
];
function filterScoreValues(input){
  var array = input.map(function (i) {
    return i.topicscore;
  });

  array.forEach(function(x, index){
    input[index].topicscore = Math.ceil(x / Math.max.apply(null, array) * 10) + 5;
  });

  return input;
 };
console.log(filterScoreValues(nodes));