foreach 语句中的 JavaScript Infinity 循环[关闭]

Question

我写了这段代码，他在无限循环中执行

    var listStock=[{"price":200,"libelle":"bus"},{"price":5,"libelle":"grand taxi"},{"price":6,"libelle":"tram"},{"price":12,"libelle":"tram"},{"price":95,"libelle":"librairie"},{"price":22,"libelle":"food"},{"price":6,"libelle":"tram"},{"price":6,"libelle":"tram"},{"price":15,"libelle":"grand taxi"},{"price":7.5,"libelle":"grand taxi"},{"price":7.5,"libelle":"grand taxi"},{"price":23,"libelle":"grand taxi"},{"price":12,"libelle":"tram"},{"price":10.5,"libelle":"food"},{"price":23,"libelle":"grand taxi"},{"price":7.5,"libelle":"grand taxi"},{"price":13.5,"libelle":"librairie"},{"price":20,"libelle":"librairie"},{"price":20,"libelle":"arrondissement"},{"price":15,"libelle":"grand taxi"},{"price":9,"libelle":"librairie"},{"price":34,"libelle":"food"},{"price":10,"libelle":"librairie"},{"price":7.5,"libelle":"grand taxi"},{"price":3.5,"libelle":"food"},{"price":23,"libelle":"grand taxi"},{"price":12,"libelle":"tram"},{"price":7.5,"libelle":"grand taxi"},{"price":33,"libelle":"tran"},{"price":4,"libelle":"pisri"},{"price":15,"libelle":"grand taxi"},{"price":5,"libelle":"pisri"},{"price":20,"libelle":"tobis"},{"price":6,"libelle":"grand taxi"},{"price":45,"libelle":"grand taxi"},{"price":7.5,"libelle":"grand taxi"},{"price":4,"libelle":"librairie"},{"price":7.5,"libelle":"grand taxi"},{"price":120,"libelle":"tran"},{"price":3,"libelle":"librairie"},{"price":8,"libelle":"pisri"},{"price":60,"libelle":"covoiturage"},{"price":7,"libelle":"grand taxi"},{"price":7,"libelle":"tram"},{"price":2,"libelle":"pisri"},{"price":1,"libelle":"gift"},{"price":29,"libelle":"food"},{"price":23,"libelle":"covoiturage"}];

var listLib=[];
listStock.forEach(function(item, index) {
  var lib=item.libelle;var pr=item.price;
  if(listLib.length==0){
    var objet={};objet.libelle=lib;objet.price=pr;
    listLib.push(objet);
  }else{
    listLib.forEach(function(item1,index1){
      if(item1.libelle==lib){
        item1.price=item1.price+pr;
      }else{
        var objet={};objet.libelle=lib;objet.price=pr;
        listLib.push(objet);
      }
    });
  }
});

我想按标签汇总价格

Answer 1

您在listLib 的循环内使用listLib.push，并且您正在为对象不匹配的每个 迭代执行此操作。所以你反复向listLib添加一个类似的对象。

您应该只找到匹配的条目，并可能在搜索之后添加一个新对象，而不是在搜索期间。因此，如果我们坚持您的代码，那么您的代码的else 部分应修改为：

    var found = false;
    for (let item1 of listLib) {
      if(item1.libelle==lib){
        item1.price=item1.price+pr;
        found = true;
        break; // No need to look further
      }
    }
    // And then AFTER the loop, check if we need to add the object:
    if (!found) {
        var objet={};objet.libelle=lib;objet.price=pr;
        listLib.push(objet);
    }

更好的是首先使用 Map 键入您的输入数据。因为这样查找起来很容易并且性能更好：

var listStock=[{"price":200,"libelle":"bus"},{"price":5,"libelle":"grand taxi"},{"price":6,"libelle":"tram"},{"price":12,"libelle":"tram"},{"price":95,"libelle":"librairie"},{"price":22,"libelle":"food"},{"price":6,"libelle":"tram"},{"price":6,"libelle":"tram"},{"price":15,"libelle":"grand taxi"},{"price":7.5,"libelle":"grand taxi"},{"price":7.5,"libelle":"grand taxi"},{"price":23,"libelle":"grand taxi"},{"price":12,"libelle":"tram"},{"price":10.5,"libelle":"food"},{"price":23,"libelle":"grand taxi"},{"price":7.5,"libelle":"grand taxi"},{"price":13.5,"libelle":"librairie"},{"price":20,"libelle":"librairie"},{"price":20,"libelle":"arrondissement"},{"price":15,"libelle":"grand taxi"},{"price":9,"libelle":"librairie"},{"price":34,"libelle":"food"},{"price":10,"libelle":"librairie"},{"price":7.5,"libelle":"grand taxi"},{"price":3.5,"libelle":"food"},{"price":23,"libelle":"grand taxi"},{"price":12,"libelle":"tram"},{"price":7.5,"libelle":"grand taxi"},{"price":33,"libelle":"tran"},{"price":4,"libelle":"pisri"},{"price":15,"libelle":"grand taxi"},{"price":5,"libelle":"pisri"},{"price":20,"libelle":"tobis"},{"price":6,"libelle":"grand taxi"},{"price":45,"libelle":"grand taxi"},{"price":7.5,"libelle":"grand taxi"},{"price":4,"libelle":"librairie"},{"price":7.5,"libelle":"grand taxi"},{"price":120,"libelle":"tran"},{"price":3,"libelle":"librairie"},{"price":8,"libelle":"pisri"},{"price":60,"libelle":"covoiturage"},{"price":7,"libelle":"grand taxi"},{"price":7,"libelle":"tram"},{"price":2,"libelle":"pisri"},{"price":1,"libelle":"gift"},{"price":29,"libelle":"food"},{"price":23,"libelle":"covoiturage"}];

let map = new Map(listStock.map(({libelle}) => [libelle, {libelle, price: 0}]));
for (let {price, libelle} of listStock) map.get(libelle).price += price;
let result = Array.from(map.values());

console.log(result);

Answer 2

var listStock=JSON.parse(`[{"price":200,"libelle":"bus"},{"price":5,"libelle":"grand taxi"},{"price":6,"libelle":"tram"},{"price":12,"libelle":"tram"},{"price":95,"libelle":"librairie"},{"price":22,"libelle":"food"},{"price":6,"libelle":"tram"},{"price":6,"libelle":"tram"},{"price":15,"libelle":"grand taxi"},{"price":7.5,"libelle":"grand taxi"},{"price":7.5,"libelle":"grand taxi"},{"price":23,"libelle":"grand taxi"},{"price":12,"libelle":"tram"},{"price":10.5,"libelle":"food"},{"price":23,"libelle":"grand taxi"},{"price":7.5,"libelle":"grand taxi"},{"price":13.5,"libelle":"librairie"},{"price":20,"libelle":"librairie"},{"price":20,"libelle":"arrondissement"},{"price":15,"libelle":"grand taxi"},{"price":9,"libelle":"librairie"},{"price":34,"libelle":"food"},{"price":10,"libelle":"librairie"},{"price":7.5,"libelle":"grand taxi"},{"price":3.5,"libelle":"food"},{"price":23,"libelle":"grand taxi"},{"price":12,"libelle":"tram"},{"price":7.5,"libelle":"grand taxi"},{"price":33,"libelle":"tran"},{"price":4,"libelle":"pisri"},{"price":15,"libelle":"grand taxi"},{"price":5,"libelle":"pisri"},{"price":20,"libelle":"tobis"},{"price":6,"libelle":"grand taxi"},{"price":45,"libelle":"grand taxi"},{"price":7.5,"libelle":"grand taxi"},{"price":4,"libelle":"librairie"},{"price":7.5,"libelle":"grand taxi"},{"price":120,"libelle":"tran"},{"price":3,"libelle":"librairie"},{"price":8,"libelle":"pisri"},{"price":60,"libelle":"covoiturage"},{"price":7,"libelle":"grand taxi"},{"price":7,"libelle":"tram"},{"price":2,"libelle":"pisri"},{"price":1,"libelle":"gift"},{"price":29,"libelle":"food"},{"price":23,"libelle":"covoiturage"}]`);

//console.log(listStock)
const finalData=listStock.reduce((acc,curr)=>{

const label=curr.libelle;
  acc[label]=acc[label]? acc[label]+ curr.price : curr.price || 0;

  return acc;
},{})

console.log(finalData)

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