Trying to build a recursion function using jQuery/JavaScript

Question

I'm currently trying to build a function that traverse through a nested object looking for a value that matches. I created this custom code that checks each levels of object. The problem how can repeat the function multiple times until it fetches or match with the value I'm looking for traversing to multiple levels.

let animalTree = {
    "animals":[
      {
        "species":"Vertebrates", 
        "types": [
            {
                "category": "Fish",
            },
            {
                "category": "Amphibians",
            },
            {
                "category": "Reptiles",
            },
            {
                "category": "Birds",
            },
            {
                "category": "Mammals",
            }
        ]
      }, 
      {
        "species":"Invertebrates", 
      },
      {
        "species":"Annelids", 
      },
      {
        "species":"Molluscs", 
      },
      {
        "species":"Nematodes", 
      },
      {
        "species":"Arthropods", 
      },
    ],
}





let scanTree = () => {

    let matchValue = "Vertebrates";

    for (let i = 0; i < animalTree.length; i++){

        if (animalTree[i].species == matchValue){
            console.log('Found')
        }
    }
}

let jParse = JSON.stringify(animalTree);

scanTree();

Is it like your match value can be either category of specie why do you want to run your function recursively ? — mickl
– mickl, Commented Dec 12, 2019 at 2:33
If there where a second item in your JSON what would that look like? Are you saying there could be another animals object? Your question is a little confusing - you shouldn't need to write your own function for this.. — Matt Oestreich
– Matt Oestreich, Commented Dec 12, 2019 at 2:59
There is no JSON in this question. JSON is a text format. What you have is an object. No need for any (additional) special jargon. — Heretic Monkey
– Heretic Monkey, Commented Dec 12, 2019 at 3:16

mickl · Accepted Answer · 2019-12-12 03:00:10Z

Not sure what your key names might be so providing generic function using Object.values() - let me know if you only expect key names to be species - will simplify then

let animalTree = {
    "animals":[
      {
        "species":"Vertebrates", 
        "types": [
            {
                "category": "Fish",
            },
            {
                "category": "Amphibians",
            },
            {
                "category": "Reptiles",
            },
            {
                "category": "Birds",
            },
            {
                "category": "Mammals",
            }
        ]
      }, 
      {
        "species":"Invertebrates", 
      },
      {
        "species":"Annelids", 
      },
      {
        "species":"Molluscs", 
      },
      {
        "species":"Nematodes", 
      },
      {
        "species":"Arthropods", 
      },
    ],
}

let matchValue = "Birds";

let scan = (array) => {
  for(let item of array) {      
      for(let value of Object.values(item)){
          if(typeof value === "string" && value === matchValue) {
              return item;
          } else if (Array.isArray(value)) {
             return scan(value);
          }
      }
  }
}


let result = scan(animalTree.animals);
console.log(result);

symlink · Accepted Answer · 2019-12-12 04:17:22Z

Use JSON.stringify() and a regular expression to simplify things:

const scanTree = (str) => { 
   const arr = JSON.stringify(animalTree).match(/"\w+":\s?"\w+"/g);
   const res = arr.filter((el) => el.indexOf(str) > -1);
   return res.map(val => JSON.parse("{" + val + "}"));
}

const animalTree = {
    "animals":[
      {
        "species":"Vertebrates", 
        "types": [
            {
                "category": "Fish",
            },
            {
                "category": "Amphibians",
            },
            {
                "category": "Reptiles",
            },
            {
                "category": "Birds",
            },
            {
                "category": "Mammals",
            }
        ]
      }, 
      {
        "species":"Invertebrates", 
      },
      {
        "species":"Annelids", 
      },
      {
        "species":"Molluscs", 
      },
      {
        "species":"Nematodes", 
      },
      {
        "species":"Arthropods", 
      },
    ],
};

const scanTree = (str) => { 
   const arr = JSON.stringify(animalTree).match(/"\w+":\s?"\w+"/g);
   const res = arr.filter((el) => el.indexOf(str) > -1);
   return res.map(val => JSON.parse("{" + val + "}"));
}

console.log(scanTree("Birds"));

Amit Sinha · Accepted Answer · 2019-12-12 03:38:40Z

let animalTree = {
        "animals":[
          {
            "species":"Vertebrates", 
            "types": [
                {
                    "category": "Fish",
                },
                {
                    "category": "Amphibians",
                },
                {
                    "category": "Reptiles",
                },
                {
                    "category": "Birds",
                },
                {
                    "category": "Mammals",
                }
            ]
          }, 
          {
            "species":"Invertebrates", 
          },
          {
            "species":"Annelids", 
          },
          {
            "species":"Molluscs", 
          },
          {
            "species":"Nematodes", 
          },
          {
            "species":"Arthropods", 
          },
        ],
    }

    let scanTree = () => {
        var flag = 0;
        let matchValue = "Vertebrates";
        for(let i = 0 ; i < animalTree.animals.length ; i++ ){
            if(animalTree.animals[i].species == matchValue){
                flag = 1;
                console.log("found");
                break;
            }
            else{
                flag = 0;
            }
        }
        if(!flag){
            console.log("not found")
        }
    }

    //let jParse = JSON.stringify(animalTree);

    scanTree();

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