Differences between JS traversal arrays and objects and detailed explanation of methods for recursively traversing objects, arrays, and attributes. js records

Differences between JS traversal arrays and objects and detailed explanation of methods for recursively traversing objects, arrays, and attributes. js records

Let's go straight to the topic. The specific code is as follows:

<Script> // ---------------- for Traversing array objects -- var I, myArr = [1, 2, 3]; for (var I = 0; I <myArr. length; I ++) {console. log (I + ":" + myArr [I]) ;}; // --------- for-in is used to traverse non-array objects var man = {hands: 2, legs: 2, heads: 1}; // Add the clone method for all objects, that is, add the prototype attribute to the built-in prototype (object, Array, function). This method is very powerful, it is also dangerous if (typeof Object. prototype. clone = "undefined") {Object. prototype. clone = function () {};}// for (var I in man) {if (man. hasOwnProperty (I) {// filter, only the private property console of man is output. log (I, ":", man [I]) ;}/// the output result is print hands: 2, legs: 2, heads: 1 for (var I in man) {// do not use the filter console. log (I, ":", man [I]);} // The output result is // hands: 2 index.html: 20 // legs: 2 index.html: 20 // heads: 1 index.html: 20 // clone: function () {}for (var I in man) {if (Object. prototype. hasOwnProperty. call (man, I) {// filter the console. log (I, ":", man [I]) ;}// the output result is print hands: 2, legs: 2, heads: 1 </script>

Next, we will introduce js recursive traversal objects, arrays, and attributes.

When working on the front-end, we sometimes need to traverse some unknown objects. The Code is as follows:

// Js traversal object
Function TraversalObject (obj)
{
For (var a in obj ){
If (typeof (obj [a]) = "object "){
TraversalObject (obj [a]); // recursive Traversal
}
Else {
Alert (a + "=" + obj [a]); // The value is displayed.
}
}
}

// Traverse all Ur values in the object
Function TraversalObject (obj)
{
For (var a in obj ){

If (a = "Url") alert (obj [a]); // display the URL Value
If (typeof (obj [a]) = "object "){
TraversalObject (obj [a]); // recursive Traversal
}
}
}

This Traversal method plays a very good role when the object is irregular but needs to obtain the same attribute.