You can use Object.keys() to get the length of the object in JavaScript. This doesn’t have to modify any existing prototype since Object.keys() is now built-in.
Let’s see HTML example code:
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Here’s an update as of 2016 and the widespread deployment of ES5 and beyond. For IE9+ and all other modern ES5+ capable browsers.
<!DOCTYPE HTML>
<html>
<body>
<script>
const myObject = new Object();
myObject["firstname"] = "John";
myObject["lastname"] = "Ken";
myObject["age"] = 21;
var size = Object.keys(myObject).length;
console.log(size);
</script>
</body>
</html> Creating a function to get the length of the object.
<!DOCTYPE HTML>
<html>
<body>
<script>
const myObject = new Object();
myObject["firstname"] = "John";
myObject["lastname"] = "Ken";
myObject["age"] = 21;
Object.size = function(obj) {
var size = 0,
key;
for (key in obj) {
if (obj.hasOwnProperty(key)) size++;
}
return size;
};
// Get the size of an object
var size = Object.size(myObject);
console.log(size);
</script>
</body>
</html> Output:
Same code for Object Array
<!DOCTYPE HTML>
<html>
<body>
<script>
let cars = [
{
"color": "purple",
"type": "minivan",
"registration": new Date('2017-01-03'),
"capacity": 7
},
{
"color": "red",
"type": "station wagon",
"registration": new Date('2018-03-03'),
"capacity": 5
}];
Object.size = function(obj) {
var size = 0,
key;
for (key in obj) {
if (obj.hasOwnProperty(key)) size++;
}
return size;
};
// Get the size of an object
var size = Object.size(cars);
console.log(size);
</script>
</body>
</html> Output: 2
Do comment if you have any doubts and suggestions on this JS Object Array topic.
Note: The All JS Examples codes are tested on the Firefox browser and the Chrome browser.
OS: Windows 10
Code: HTML 5 Version