An array can be used to store a collection in JavaScript
var arr = []; // empty array
arr.push('A');
arr.push('B');
arr.push('C');
alert(arr.length); // alerts 3
alert(arr[1]); // alerts B (zero based indexing)
Using JavaScript object as a hash table.
Essentially, every java-script object can have multiple properties that are essentially name-value pairs. For example,
var o = { } // empty object
o["prop1"] = "A"; // Added property named prop1 with value "A"
o["prop2"] = "B"; // Added property named prop2 with value "B"
o["prop3"] = "C"; // Added property named prop2 with value "C"
alert(o["prop1"]); // alerts A
alert(o.prop2); // alerts B - notice alternate syntax
alert(o["prop4"]); // alerts undefined - because we are accessing non-existent property
if (o["prop3"]) {
alert("prop3 exists"); // to check for some property
}
for (p in o) { // iterate all properties
alert(p); // alerts property name
alert(o[p]); // alerts property value
}