JavaScript中的for循環功能內的for循環

Question

我有一個for循環，應該循環通過一個對象。 但是此對象內部可以具有許多其他對象級別。 我怎樣才能使一個功能，應該讓for循環內for循環，因為我想為多層次的深淵？

像這樣， lvl變量將是它應該潛入的級別數：

var lvl = 5;

for (var i = 0; i < groups.length; i++) {
    var groups = groups[i];

    for (var i = 0; i < groups.length; i++) {
        var groups = groups[i];

        for (var i = 0; i < groups.length; i++) {
            var groups = groups[i];

        }
    }
}

例如，如果我有以下對象樹：

var foo = {
  child: {
    grand:{
      greatgrand: {
      }
    }
  }
}

如何僅通過跳到foo對象中的特定級別來控制台記錄所有對象樹名稱？

dive(2); // would dive to level two (grand)

// would return the following in the console
child
grand

Answer 1

遞歸函數（一個可以自我調用的函數）是解決之道。 您想要這樣的東西：

/* pseudo-code; this will not run */
function processThing(thing) {
  if (thing is an object) {
    // process all of thing's properties
    for (property in thing) {
      processThing(property);
    }
  }
  else {
    // process thing as a value
  }
}

Answer 2

干得好。 我已經編寫了一個遞歸函數，它將迭代一個對象圖。 您可以為遍歷函數提供depth參數。

一個JSFiddle在這里 。 請檢查開發者工具控制台的輸出。
帶有縮進的小提琴在這里

var obj = {
firstName: "John",
lastName: "Doe",
address1A: {
    street: "120 Washington St",
    city: "Mountain View",
    state: "CA",
    address2A: {
        street: "100 Washington st",
        city: "Mountain View",
        state: "CA",
        address3A: {
            street: "150 Washington st",
            city: "Mountain View",
            state: "CA",
            address4A: {
                street: "150 Washington st",
                city: "Mountain View",
                state: "CA",
            }
        }
    }
},
address1B: {
    street: "120 Washington St",
    city: "Mountain View",
    state: "CA",
    address2B: {
        street: "100 Washington st",
        city: "Mountain View",
        state: "CA",
        address3B: {
            street: "150 Washington st",
            city: "Mountain View",
            state: "CA",
            address4B: {
                street: "150 Washington st",
                city: "Mountain View",
                state: "CA",
            }
        }
    }
}
};

function traverse(initObj, depth) {
     depthTraversal(initObj, depth, 1);
}

function depthTraversal(objArg, depthArg, counterArg) {
    //create a closure for remembering loop variables
    return (function (myObj, myDepth, counter) {
        //console.log(myDepth + " - " + counter);
        if (myDepth < counter) {
          return;
        }
       //console.log(myObj);
       for (var prop in myObj) {
          //console.log(prop + " :" + typeof (myObj[prop]));
          if (myObj.hasOwnProperty(prop)) {
             if (typeof (myObj[prop]) === "object") {
                console.log(prop);
                depthTraversal(myObj[prop], myDepth, counter + 1);
             }
          }
      }
}(objArg, depthArg, counterArg)); //IIFE
};


traverse(obj, 4);