Search results
Feb 17, 2012 · Loop using forEach. forEach is a function which is located on Array.prototype which takes a callback function as an argument. It then executes this callback function for every element in the array. In contrast to the map() function, the forEach function returns nothing (undefined).
console.log(key, dictionary[key]); } } 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]); });
Jun 2, 2016 · 62. The p-iteration module on npm implements the Array iteration methods so they can be used in a very straightforward way with async/await. An example with your case: const { forEach } = require('p-iteration'); const fs = require('fs-promise'); (async function printFiles () {. const files = await getFilePaths();
May 31, 2017 · Now I want to update them into the database so I need to walk them. I tried: console.log('value: ' + value + ', key: ' + key + ', map:' + map); And then the console report an error: object.forEach is not a function. forEach should be invoked on arrays not with an object. If you try on array of objects , it will work.
The forEach method was introduced with lineage to the prototypal inheritance of Array object! Needless to say, the forEach clause works only with those data structure which are Arrays. The method basically iterates over the elements of the array and executes a callback function [basically some executable function/ fun activity].
Jan 17, 2013 · I would agree here, were it not for ECMA-262 defining an array as an object having a forEach(), map(), reduce(), filter(), which all take callbacks receiving the order [value, index, array]. An object in JS can be understood as just another collection; and then these methods become unified in their parameters of [value, key|index, context] (this is what lodash and underscore are doing).
Jun 7, 2011 · I can think of three ways to fake it, though. 1. The Ugly Way: pass a second argument to forEach to use as context, and store a boolean in there, then use an if. This looks awful. 2. The Controversial Way: surround the whole thing in a try-catch block and throw an exception when you want to break.
May 14, 2019 · The forEach function doesn't return a the value you're expecting it to , which means that your isUniform function will always return true. For what you're trying to do, you could use an old-fashioned for loop, or use array.every(isTheSame) .
If you care about performance use .forEach and ignore next calls when you have your result, this is the most efficient way to do it in ES5. Note that ES5 doesn't have Map so your are probably using a polyfill like core-js , native objects ( {} ) are faster in this case and can be iterated using for(var key in object) .
Mar 31, 2014 · You can't use for / in on NodeList s or HTMLCollection s. However, you can use some Array.prototype methods, as long as you .call() them and pass in the NodeList or HTMLCollection as this. So consider the following as an alternative to jfriend00's for loop: var list= document.getElementsByClassName("events");
