当过滤器排除了孩子的父母时，如何在array.filter（）回调函数中获得孩子的父母？

Question

Today I discovered the array.filter() method and its associated callback function.

I have an array of objects that looks like this:

var treeAry = [
      {"id" : "200", "parent": "#", "type" : "1"},
      {"id" : "300", "parent": "#", "type" : "1"},
      {"id" : "400", "parent": "#", "type" : "1"},
      {"id" : "500", "parent": "300", "type" : "5"},
      {"id" : "600", "parent": "300", "type" : "5"},
      {"id" : "700", "parent": "400", "type" : "5"},
      {"id" : "800", "parent": "400", "type" : "5"},
      {"id" : "900", "parent": "200", "type" : "6"},
      {"id" : "1000", "parent": "200", "type" : "9"},
      {"id" : "1100", "parent": "200", "type" : "8"},
];

I was successfully able to filter for type 5:

  filteredAry = [];

  filteredAry = treeAry.filter(function(val, index, ary){

    /*get all type 5*/
    return val.type === '5';

    /*get all type 5 or type 1*/
    //return val.type === '1' || val.type === '5';

  });

  console.dir(filteredAry)

Here's my question:

Although I'm able to filter for type 5, I also need Type 5's parents (a child's parent references the id , and a parent can be a #). Essentially, my results should include anything with type 5, and then also record id 300 and 400 . It should not include id 200 .

Should I run some sort of for each loop on filteredAry[] to find and push the corresponding item in treeAry[] ? Shouldn't I be able to use the index and ary arguments to get the parents somehow?

Sorry, I don't know how to do this and would love your help. Just need a push in the right direction, Thank you!

Answer 1

Try this:

 var treeAry = [ {"id" : "200", "parent": "#", "type" : "1"}, {"id" : "300", "parent": "#", "type" : "1"}, {"id" : "400", "parent": "#", "type" : "1"}, {"id" : "500", "parent": "300", "type" : "5"}, {"id" : "600", "parent": "300", "type" : "5"}, {"id" : "700", "parent": "400", "type" : "5"}, {"id" : "800", "parent": "400", "type" : "5"}, {"id" : "900", "parent": "200", "type" : "6"}, {"id" : "1000", "parent": "200", "type" : "9"}, {"id" : "1100", "parent": "200", "type" : "8"}, ]; var result = treeAry.filter(value => { return value.type === '5' || treeAry.filter(val => val.parent === value.id && val.type === '5').length > 0; }); console.log(result) 

You can replace lambdas (arrow functions) with ordinary functions if ES6 is an issue.

Answer 2

One way would be

 var treeAry = [ {"id" : "200", "parent": "#", "type" : "1"}, {"id" : "300", "parent": "#", "type" : "1"}, {"id" : "400", "parent": "#", "type" : "1"}, {"id" : "500", "parent": "300", "type" : "5"}, {"id" : "600", "parent": "300", "type" : "5"}, {"id" : "700", "parent": "400", "type" : "5"}, {"id" : "800", "parent": "400", "type" : "5"}, {"id" : "900", "parent": "200", "type" : "6"}, {"id" : "1000", "parent": "200", "type" : "9"}, {"id" : "1100", "parent": "200", "type" : "8"}, ]; filteredAry = []; filteredAry = treeAry.filter(function(val, index, ary){ /*get all type 5*/ return val.type === '5' || ary.some(function(item){ return item.parent === val.id && item.type==='5'; }); }); console.dir(filteredAry)