First you should know what JSON is: It is language agnostic data-interchange format. The syntax of JSON was inspired by the JavaScript Object Literal notation, but there are differences between them. For example, in JSON all keys must be quoted, while in object literals this is not necessary: // JSON: { “foo”: “bar” } // … Read more
You can use an utility function like this: get = function(obj, key) { return key.split(“.”).reduce(function(o, x) { return (typeof o == “undefined” || o === null) ? o : o[x]; }, obj); } Usage: get(user, ‘loc.lat’) // 50 get(user, ‘loc.foo.bar’) // undefined Or, to check only if a property exists, without getting its value: has … Read more
It can be as simple as that: const sumValues = obj => Object.values(obj).reduce((a, b) => a + b, 0); Quoting MDN: The Object.values() method returns an array of a given object’s own enumerable property values, in the same order as that provided by a for…in loop (the difference being that a for-in loop enumerates properties … Read more
Although JS implementations might keep track of such a value internally, there’s no standard way to get it. In the past, Mozilla’s Javascript variant exposed the non-standard __count__, but it has been removed with version 1.8.5. For cross-browser scripting you’re stuck with explicitly iterating over the properties and checking hasOwnProperty(): function countProperties(obj) { var count … Read more
Simply const obj = {}; for (const key of yourArray) { obj[key] = whatever; } or if you prefer “functional” style: const obj = yourArray.reduce((o, key) => Object.assign(o, {[key]: whatever}), {}); using the modern object spread operator: const obj = yourArray.reduce((o, key) => ({ …o, [key]: whatever}), {}) Example: [ { id: 10, color: “red” … Read more
Thanks for the comment, tec. I was able to find an existing unconfirmed Webkit bug that explains this issue: https://bugs.webkit.org/show_bug.cgi?id=35801 (EDIT: now fixed!) There appears to be some debate regarding just how much of a bug it is and whether it’s fixable. It does seem like bad behavior to me. It was especially troubling to … Read more
It’s actually very straight forward with jQuery’s $.map var arr = $.map(obj, function(el) { return el }); FIDDLE and almost as easy without jQuery as well, converting the keys to an array and then mapping back the values with Array.map var arr = Object.keys(obj).map(function(k) { return obj[k] }); FIDDLE That’s assuming it’s already parsed as … Read more
I’ve found that the following works if you’re not using jQuery and only interested in cloning simple objects (see comments). JSON.parse(JSON.stringify(json_original)); Documentation JSON.parse() JSON.stringify()
This is good for shallow cloning. The object spread is a standard part of ECMAScript 2018. For deep cloning you’ll need a different solution. const clone = {…original} to shallow clone const newobj = {…original, prop: newOne} to immutably add another prop to the original and store as a new object.
With ES6, you may deconstruct each object to create new one without named attributes: const newArray = array.map(({dropAttr1, dropAttr2, …keepAttrs}) => keepAttrs)