No, it is blocking. Have a look at the specification of the algorithm. However a maybe easier to understand implementation is given on MDN: if (!Array.prototype.forEach) { Array.prototype.forEach = function(fun /*, thisp */) { “use strict”; if (this === void 0 || this === null) throw new TypeError(); var t = Object(this); var len = … Read more
The callback is passed the element, the index, and the array itself. arr.forEach(function(part, index, theArray) { theArray[index] = “hello world”; }); edit — as noted in a comment, the .forEach() function can take a second argument, which will be used as the value of this in each call to the callback: arr.forEach(function(part, index) { this[index] … Read more
for (var k in target){ if (target.hasOwnProperty(k)) { alert(“Key is ” + k + “, value is ” + target[k]); } } hasOwnProperty is used to check if your target really has that property, rather than having inherited it from its prototype. A bit simpler would be: for (var k in target){ if (typeof target[k] … Read more
for…in iterates over property names, not values, and does so in an unspecified order (yes, even after ES6). You shouldn’t use it to iterate over arrays. For them, there’s ES5’s forEach method that passes both the value and the index to the function you give it: var myArray = [123, 15, 187, 32]; myArray.forEach(function (value, … Read more
If you prefer a solution that does not require the initialization of the counter outside the loop, then you can compare the current iteration key against the function that tells you the last / first key of the array. PHP 7.3 and newer: foreach ($array as $key => $element) { if ($key === array_key_first($array)) { … Read more
While you can use a ForEach extension method, if you want to use just the framework you can do collection.Select(c => {c.PropertyToSet = value; return c;}).ToList(); The ToList is needed in order to evaluate the select immediately due to lazy evaluation.
foreach($array as $key=>$value) { // do stuff } $key is the index of each $array element
To safely remove from a collection while iterating over it you should use an Iterator. For example: List<String> names = …. Iterator<String> i = names.iterator(); while (i.hasNext()) { String s = i.next(); // must be called before you can call i.remove() // Do something i.remove(); } From the Java Documentation : The iterators returned by … Read more
From For statements with range clause: A “for” statement with a “range” clause iterates through all entries of an array, slice, string or map, or values received on a channel. For each entry it assigns iteration values to corresponding iteration variables and then executes the block. As an example: for index, element := range someSlice … Read more
There is no ForEach extension for IEnumerable; only for List<T>. So you could do items.ToList().ForEach(i => i.DoStuff()); Alternatively, write your own ForEach extension method: public static void ForEach<T>(this IEnumerable<T> enumeration, Action<T> action) { foreach(T item in enumeration) { action(item); } }