Skip to content

Instantly share code, notes, and snippets.

Embed
What would you like to do?
Simple deep equality comparison in Javascript (ES5+)
// Deep Equality comparison example
//
// This is an example of how to implement an object-comparison function in
// JavaScript (ES5+). A few points of interest here:
//
// * You can get an array of all an object's properties in ES5+ by calling
// the class method Object.keys(obj).
// * The function recursively calls itself in the for / in loop when it
// compares the contents of each property
// * You can hide a "private" function inside a function of this kind by
// placing one function declaration inside of another. The inner function
// is not hoisted out into the global scope, so it is only visible inside
// of the parent function.
// * The reason this nested helper function is necessary is that
// `typeof null` is still "object" in JS, a major "gotcha" to watch out for.
//
function deepEqual(obj1, obj2) {
if (obj1 === obj2) {
return true;
} else if (isObject(obj1) && isObject(obj2)) {
if (Object.keys(obj1).length !== Object.keys(obj2).length) { return false; }
for (var prop in obj1) {
if (!deepEqual(obj1[prop], obj2[prop])) {
return false;
}
}
return true;
}
// Private
function isObject(obj) {
if (typeof obj === "object" && obj != null) {
return true;
} else {
return false;
}
}
}
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
You can’t perform that action at this time.