How to use get the value from the nth child key of the object by using variable?

You need an object for foo, because foo is a primitive type.

var object = {}; object.foo = "foo"; object.foo.bar = "bar"; // does not work! 

This works

var object = {}; object.foo = {}; object.foo.bar = "bar"; // work! 

When you do

var object = {}; object.foo = "foo"; 

You define the property as string and it won't store the keys since it is a string literal not a string object.

you need to try

var object = {}; object.foo = new String("foo"); 

Now it can store more properties in object.foo.

var object = {}; object.foo = new String( "foo" ); object.foo.bar = new String( "bar" ); object.foo.bar.alice = new String( "alice" ); object.foo.bar.alice.bob = new String( "bob" ); console.log( object );

you need to assign as a object {key:value,key:value}

object.foo = {0:"foo",bar:{}}; object.foo.bar = {0:"bar",alice:{}}; object.foo.bar.alice = {0:"alice",bob:{}}; object.foo.bar.alice.bob = "bob"; console.log(object.foo.bar.alice); console.log(object.foo.bar.alice.bob); 

You can develop a simple function to get the nested objects and their keys dynamically. Such as the following. A similar approach would be sufficient for the set version as well.

Object.prototype.getNestedValue = function(...a) { return a.length > 1 ? (this[a[0]] !== void 0 && this[a[0]].getNestedValue(...a.slice(1))) : this[a[0]]; }; var arr = [{fox: [{turn:[857, 432]}]}, {sax: [{pana:[777, 987]}]}, {ton: [{joni:[123, 567]}]}, {piu: [{burn:[666, 37]}]}, {sia: [{foxy:[404, 696]}]}], myObj = {foo: {bar: {alice: {bob: "bob"}}}}; document.write("<pre>" + JSON.stringify(arr.getNestedValue(3,"piu",0,"burn",1),null,2) + "</pre>"); document.write("<pre>" + JSON.stringify(arr.getNestedValue(3,"piu",0,"burn"),null,2) + "</pre>"); document.write("<pre>" + JSON.stringify(myObj.getNestedValue("foo","bar","alice","bob"),null,2) + "</pre>");

Keep in mind that you can set your nested properties in an array in the order of appearance and then call like myDeeplyNestedObj.getNestedValue(...propsArray)