将嵌套对象的每个对象的索引设置为属性

Question

Good morning !

Does anyone know how i can insert the index of each object of a nested object into an property ?

Something like this:

const myObj = 
{
  "@type": "someType",
  A: [
    {
      "@type": "someType0",
      order: "DESC",
      myIndex: 0
    },
    {
      "@type": "someType1",
      order: "DESC",
      myIndex: 1
    },
    {
      "@type": "someType2",
      order: "DESC",
      myIndex: 2
    }
  ],
  B: [],
};

Answer 1

You can use the .map function to alter the objects within array.

 const myObj = { "@type": "someType", A: [ { "@type": "someType0", order: "DESC" }, { "@type": "someType1", order: "DESC" }, { "@type": "someType2", order: "DESC" } ], B: [], }; const newA = myObj.A.map((item,index) => { item.myIndex = index; return item; }) console.log(newA); 

CodePen link: https://codepen.io/bergur/pen/rrdyKX?editors=0010

If you wanna loop through all the properties of myObj you can use Object.keys(myObj) and then go through them and alter them one by one.

Answer 2

You can do that iterating over the array and assigning i (current index of iteration) to the object property, like myObj.A.forEach((d, i) => d.myIndex = i); , where d - is current item, and i - is current index.

 const myObj = { "@type": "someType", A: [ { "@type": "someType0", order: "DESC" }, { "@type": "someType1", order: "DESC" }, { "@type": "someType2", order: "DESC" } ], B: [], }; myObj.A.forEach((d, i) => d.myIndex = i); console.log(myObj); 

Answer 3

You could use a recursive approach and add for all arrays an index.

 function setIndex(object) { Object.values(object).forEach(v => { if (Array.isArray(v)) { v.forEach((o, i) => { o.index = i; setIndex(o); }); } }); } const object = { "@type": "someType", A: [{ "@type": "someType0", order: "DESC" }, { "@type": "someType1", order: "DESC" }, { "@type": "someType2", order: "DESC" }], B: [] }; setIndex(object); console.log(object); 

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Answer 4

You can use a combination of Object.keys or Object.values and Array.forEach to achieve this. Using your 'myObject' variable as a starting point, something like this...

Using Object.keys

/* loop through keys of 'myObject' */
Object.keys(myObject).forEach(function(key) {
    /* check that 'myObject[key] is an Array &&
       loop through items in each 'myObject[key]'
       to add unique 'myIndex' property */
    Array.isArray(myObject[key]) && myObject[key].forEach(function(obj, idx) {
        obj.myIndex = idx;
    });
});

Using Object.values

/* loop through 'myObject' property values */
Object.values(myObject).forEach(function(val) {
    /* check 'val' is an Array &&
       loop through each item in 'val' 
       to add unique 'myIndex' property */
    Array.isArray(val) && val.forEach(function(obj, idx) {
        obj.myIndex = idx;
    });
});

Hope that helps. :-D

• Array.forEach @ MDN
• Array.isArray @ MDN
• Object.keys @ MDN
• Object.values @ MDN