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).

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:

2015年2月17日 · In JavaScript objects are containers for key/value pairs. How we get the value for a specific key? var model = dictionary["key1"]; or. var model = dictionary.key1; If key1 isn't a key of dictionary, then you will get as model the undefined. How we set the value for a specific key? dictionary.key5 = new Model("route5", "template5");

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.

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

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]); });

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

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.

2024年3月1日 · @Dominic either way, there's actually a sound technical reason to recommend against the Object.keys method, and that is since the values are not passed to the .map call directly the callback must form a closure over the original object to obtain them, which means it has to be in the same lexical scope.