This does not create a "normal" JavaScript object literal (aka map, aka hash, aka dictionary). It is however creating the structure that OP asked for (and which is illustrated in the other question linked to), which is an array of object literals , each with key and value properties.

2021年11月17日 · If the value comes from the user, then care needs to be taken to use Object.hasOwnProperty.call(dictionary, key) (otherwise the user can enter a value of valueOf and dictionary['valueOf'] returns the Object.valueOf() function belonging to the Object prototype which is probably not what your code would expect - potential bug or security issue).

2014年12月1日 · the most used solution and probably the worst one, you have to loop through the whole dictionary to get the length so it's O(n) instead of O(1) like it should be, ugh – RenaissanceProgrammer Commented Mar 21, 2018 at 16:24

2013年10月25日 · A JavaScript "dictionary" is called an object. Just FYI. – JJJ. Commented Oct 25, 2013 at 21:07.

2017年5月23日 · This approach makes accessing properties in JavaScript typically much slower than accessing instance variables in programming languages like Java and Smalltalk. In these languages, instance variables are located at fixed offsets determined by the compiler due to the fixed object layout defined by the object's class.

2017年5月10日 · array_keys from PHPJS ports PHP's handy array_keys function, so it can be used in JavaScript. At a glance, it uses Object.keys if supported, but it handles the case where it isn't very easily. It even includes filtering the keys based on values you might be looking for (optional) and a toggle for whether or not to use strict comparison ...

Note: The if condition above is necessary only if you want to iterate over the properties which are the dictionary object's very own. Because for..in will iterate through all the inherited enumerable properties. Or. Object.keys(dictionary).forEach(function(key) { console.log(key, dictionary[key]); });

2019年7月17日 · Javascript's Map closely resembles a dictionary. Its instances sport handy has , get , set , keys , values methods. It's also directly iterable via a forEach method.

2009年7月8日 · That question puzzles me. In Javascript, there are at least two references for absent objects to avoid problems like this: null and undefined. null is the primitive value that represents the intentional absence of any object value, or in short terms, the confirmed lack of value. On the other hand, undefined is an unknown value (not defined).

2020年7月11日 · Here's a dictionary that will take any type of key as long as the toString() property returns unique values. The dictionary uses anything as the value for the key value pair. See Would JavaScript Benefit from a Dictionary Object. To use the dictionary as is: