Ccna final exam - java, php, javascript, ios, cshap all in one. This is a collaboratively edited question and answer site for professional and enthusiast programmers. It's 100% free, no registration required.
An array is not an associative array, however the array object is an object, and all objects are associative arrays. If you use a string as key when assigning items to the array, you are not using it as an array, you are using it as an object.
The length property of the array returns how many items you have stored in the array. If you also use the array object as an associative array, that won't affect how you use the array as an array.
There is no length when you store objects, only when you use the array as intended.
Try this (DEMO)
var idStruttura=2; var arrayMarkers={}; // creates a more appropriate object than []
arrayMarkers["sede_"+idStruttura] = "ciao"; arrayMarkers["sede_"+(++idStruttura)] = "espresso"; var len = 0; for (var o in arrayMarkers) { if (arrayMarkers.hasOwnProperty(o)) len++; } arrayMarkers.length=len alert(arrayMarkers.length)
What you've created is a regular array object and added a property to it called sede_.... JavaScript doesn't use associative arrays in the same way a language like PHP does. Arrays are objects that can have properties, but those properties are not among the numerically indexed array elements.
var idStruttura=2; var arrayMarkers=new Array();
// Push an object onto the array having one property: arrayMarkers.push({"sede_" + idStruttura : "ciao"});
// Or declare it as an object to begin with: // This makes more sense.... var objMarkers = {}; objMarkers['sede_' + id] = 'ciao';
An array is not an associative array, however the array object is an object, and all objects are associative arrays. If you use a string as key when assigning items to the array, you are not using it as an array, you are using it as an object.
ReplyDeleteThe length property of the array returns how many items you have stored in the array. If you also use the array object as an associative array, that won't affect how you use the array as an array.
There is no length when you store objects, only when you use the array as intended.
ReplyDeleteTry this (DEMO)
var idStruttura=2;
var arrayMarkers={}; // creates a more appropriate object than []
arrayMarkers["sede_"+idStruttura] = "ciao";
arrayMarkers["sede_"+(++idStruttura)] = "espresso";
var len = 0;
for (var o in arrayMarkers) {
if (arrayMarkers.hasOwnProperty(o)) len++;
}
arrayMarkers.length=len
alert(arrayMarkers.length)
What you've created is a regular array object and added a property to it called sede_.... JavaScript doesn't use associative arrays in the same way a language like PHP does. Arrays are objects that can have properties, but those properties are not among the numerically indexed array elements.
ReplyDeletevar idStruttura=2;
var arrayMarkers=new Array();
// Push an object onto the array having one property:
arrayMarkers.push({"sede_" + idStruttura : "ciao"});
// Or declare it as an object to begin with:
// This makes more sense....
var objMarkers = {};
objMarkers['sede_' + id] = 'ciao';
array's in javascript (unlike php) cannot have string key's, only numeric keys. If you want a string literal as a key, please use objects
ReplyDeleteWhat you need is a simple Object, not an Array. Arrays have numeric indexes.
ReplyDeletevar markers = {};
markers['sede_' + id] = 'ciao';
Also note that {} is the same as new Object() and [] is the same as new Array(). Always use the former ones. It's much clear to any JS developer.