किसी भी तरह से काम करते समय, सभी उदाहरणों का ओवरकम्प्लिकेट किया जाता है:
- वे उपयोग करते हैं
new Array() , जो एक साधारण साहचर्य सरणी (AKA शब्दकोश) के लिए एक ओवरकिल (और एक ओवरहेड) है।
- बेहतर उपयोग करते हैं
new Object()। ठीक काम करता है, लेकिन यह सब अतिरिक्त टाइपिंग क्यों?
इस प्रश्न को "शुरुआती" टैग किया गया है, तो चलिए इसे सरल बनाते हैं।
उबेर-सरल तरीका जावास्क्रिप्ट में एक शब्दकोश का उपयोग करें या "क्यों जावास्क्रिप्ट में एक विशेष शब्दकोश वस्तु नहीं है?"
// create an empty associative array (in JavaScript it is called ... Object)
var dict = {}; // huh? {} is a shortcut for "new Object()"
// add a key named fred with value 42
dict.fred = 42; // we can do that because "fred" is a constant
// and conforms to id rules
// add a key named 2bob2 with value "twins!"
dict["2bob2"] = "twins!"; // we use the subscript notation because
// the key is arbitrary (not id)
// add an arbitrary dynamic key with a dynamic value
var key = ..., // insanely complex calculations for the key
val = ...; // insanely complex calculations for the value
dict[key] = val;
// read value of "fred"
val = dict.fred;
// read value of 2bob2
val = dict["2bob2"];
// read value of our cool secret key
val = dict[key];
अब मान बदलते हैं:
// change the value of fred
dict.fred = "astra";
// the assignment creates and/or replaces key-value pairs
// change value of 2bob2
dict["2bob2"] = [1, 2, 3]; // any legal value can be used
// change value of our secret key
dict[key] = undefined;
// contrary to popular beliefs assigning "undefined" does not remove the key
// go over all keys and values in our dictionary
for (key in dict) {
// for-in loop goes over all properties including inherited properties
// let's use only our own properties
if (dict.hasOwnProperty(key)) {
console.log("key = " + key + ", value = " + dict[key]);
}
}
मान हटाना भी आसान है:
// let's delete fred
delete dict.fred;
// fred is removed, the rest is still intact
// let's delete 2bob2
delete dict["2bob2"];
// let's delete our secret key
delete dict[key];
// now dict is empty
// let's replace it, recreating all original data
dict = {
fred: 42,
"2bob2": "twins!"
// we can't add the original secret key because it was dynamic,
// we can only add static keys
// ...
// oh well
temp1: val
};
// let's rename temp1 into our secret key:
if (key != "temp1") {
dict[key] = dict.temp1; // copy the value
delete dict.temp1; // kill the old key
} else {
// do nothing, we are good ;-)
}