Objects don’t have a length property, that way most time developers get JavaScript array length undefined error.
A simple solution if you know you don’t have to worry about hasOwnProperty checks would be to do this:
Object.keys(data).length;Read:
JavaScript array length undefined
Simple example code tries to get the length of an object and use for..in the loop through the object and get values.
<!DOCTYPE html>
<html>
<body>
<script>
var coordinates = {
"a": [
[1, 2],
[8, 9]
],
"b": [
[5, 8],
[2, 4]
]
};
console.log(coordinates.length);
console.log(typeof(coordinates));
for (var i in coordinates) {
console.log(coordinates[i])
}
</script>
</body>
</html>
Output:
or Object.keys
var keys = Object.keys(coordinates);
for (var i = 0, len = keys.length; i < len; i++) {
console.log(coordinates[keys[i]]);
}Do comment if you have any doubts or suggestions on this JS array length topic.
Note: The All JS Examples codes are tested on the Firefox browser and the Chrome browser.
OS: Windows 10
Code: HTML 5 Version
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