How to Compare Two Json Objects for Equality Instance Code in JS

In the front-end interview process of js, we often encounter such a pen test: How to compare two Json objects in JS to see if they are equal to the instance code. Take some time for everyone to sort out this site below, and take a look at it.

1. Prepare three tool methods to judge whether it is an object type, whether it is an array, and get the length of the object

function isObj(object) {
return object && typeof (object) == 'object' && Object.prototype.toString.call(object).toLowerCase() == "[object object]";
}
function isArray(object) {
return object && typeof (object) == 'object' && object.constructor == Array;
}
function getLength(object) {
var count = 0;
for (var i in object) count++;
return count;
}

2. Prepare two identical or different Json objects

var jsonObjA = {
"Name": "MyName",
"Company": "MyCompany",
"Infos": [
{ "Age": "100" },
{
"Box": [
{ "Height": "100" },
{ "Weight": "200" }
]
}
],
"Address": " Malan Mountain "
}
var jsonObjB = {
"Name": "MyName",
"Company": "MyCompany",
"Infos": [
{ "Age": "100" },
{
"Box": [
{ "Height": "100" },
{ "Weight": "200" }
]
}
],
"Address": " Malan Mountain 2 No. "
}

3. Main code

function Compare(objA, objB) {
if (!isObj(objA) || !isObj(objB)) return false; // Determine whether the type is correct 
if (getLength(objA) != getLength(objB)) return false; // Judge whether the length is 1 To 
return CompareObj(objA, objB, true);// Default to true
}
function CompareObj(objA, objB, flag) {
for (var key in objA) {
if (!flag) // Jump out of the whole loop 
break;
if (!objB.hasOwnProperty(key)) { flag = false; break; }
if (!isArray(objA[key])) { // When the child is not an array , Compare attribute values 
if (objB[key] != objA[key]) { flag = false; break; }
} else {
if (!isArray(objB[key])) { flag = false; break; }
var oA = objA[key], oB = objB[key];
if (oA.length != oB.length) { flag = false; break; }
for (var k in oA) {
if (!flag) // The reason for jumping out of the loop here is to prevent recursion from continuing 
break;
flag = CompareObj(oA[k], oB[k], flag);
}
}
}
return flag;
}

4. Call the method

var result = Compare(jsonObjA, jsonObjB);
console.log(result); // true or false