从js中的嵌套object中提取键值

Question

How should I extract key from a nested object If i enter Mumbai, I want to get Maharashtra and India.If The user will enter value like 'Dallas', then it should return Texas and USA

obj = {
       "India":
          {
            "Karnataka": ["Bangalore", "Mysore"],
            "Maharashtra": ["Mumbai", "Pune"]
          },
      "USA": 
          {
           "Texas": ["Dallas", "Houston"],
           "IL": ["Chicago", "Aurora", "Pune"]
          }
      }

Answer 1

Edit: After rereading the question and comments from @iAmOren.

Let's recurse through the tree. This will work for any tree depth. It will also find a State or a Country (or in other words, any key or value at any level).

Edit 2: Thanks for the feedback again, @iAmOren. Now, it finds all instead of "find first" in my last solution.

 var obj = { "India": { "Karnataka": ["Bangalore", "Mysore", "Texas"], "Maharashtra": ["Mumbai", "Pune"] }, "USA": { "Texas": ["Dallas", "Houston"], "IL": ["Chicago", "Aurora", "Pune"] } }; var getParents = function(o, toFind, found, path) { if (path === undefined) path = []; for(var key in o) { // Matches city or the parent nodes (country or state). if (o[key] === toFind || key === toFind) { var aFoundPath = Object.assign([], path); aFoundPath.push(toFind); found.push(aFoundPath); } else { if (typeof o[key] == "object") { path.push(key); getParents(o[key], toFind, found, path); path.pop(); } } } }; var printParents = function(toFind) { var outFound = []; getParents(obj, toFind, outFound); console.log(outFound); }; printParents("Mumbai"); printParents("Pune"); printParents("Texas");

Answer 2

Here's my answer from a (very) similar question. It returns an array of array of country and state.

function findCity(city) {
  var result=[];
  for(country in obj) {
    for(state in obj[country]) {
      if(obj[country][state].includes(city)) {
        result.push([country, state]);
      }
    }
  }
  return result;
}

---

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Please explain why in detail instead.
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Answer 3

You can loop through the object and find the respective keys by matching the value:

 var obj = { "India": { "Karnataka": ["Bangalore", "Mysore"], "Maharashtra": ["Mumbai", "Pune"] }, "USA": { "Texas": ["Dallas", "Houston"], "IL": ["Chicago", "Aurora", "Pune"] } } var country, state; var city = 'Mumbai'; for(var k in obj){ for(var j in obj[k]){ if(obj[k][j].includes(city)){ country = k; state = j; } } } console.log(country + ', ' + state);