The reason is that one construct: var a = []; // Create a new empty array. a[5] = 5; // Perfectly legal JavaScript that resizes the array. for (var i = 0; i < a.length; i++) { // Iterate over numeric indexes from 0 to 5, as everyone expects. console.log(a[i]); } /* Will display: undefined … Read more
foreach supports iteration over three different kinds of values: Arrays Normal objects Traversable objects In the following, I will try to explain precisely how iteration works in different cases. By far the simplest case is Traversable objects, as for these foreach is essentially only syntax sugar for code along these lines: foreach ($it as $k … Read more
Iterating over properties requires this additional hasOwnProperty check: for (var prop in obj) { if (Object.prototype.hasOwnProperty.call(obj, prop)) { // do stuff } } It’s necessary because an object’s prototype contains additional properties for the object which are technically part of the object. These additional properties are inherited from the base object class, but are still … Read more
Pure speculation is that you’re using a terminal that attempts to do word-wrapping rather than character-wrapping, and treats B as a word character but # as a non-word character. So when it reaches the end of a line and searches for a place to break the line, it sees a # almost immediately and happily … Read more
foreach(KeyValuePair<string, string> entry in myDictionary) { // do something with entry.Value or entry.Key }
Well, the problem is that the variable i, within each of your anonymous functions, is bound to the same variable outside of the function. ES6 solution: let ECMAScript 6 (ES6) introduces new let and const keywords that are scoped differently than var-based variables. For example, in a loop with a let-based index, each iteration through … Read more
You can use the for-in loop as shown by others. However, you also have to make sure that the key you get is an actual property of an object, and doesn’t come from the prototype. Here is the snippet: var p = { “p1”: “value1”, “p2”: “value2”, “p3”: “value3” }; for (var key in p) … Read more
If you’re only interested in the keys, you can iterate through the keySet() of the map: Map<String, Object> map = …; for (String key : map.keySet()) { // … } If you only need the values, use values(): for (Object value : map.values()) { // … } Finally, if you want both the key and … Read more
Three main options: for (var i = 0; i < xs.length; i++) { console.log(xs[i]); } xs.forEach((x, i) => console.log(x)); for (const x of xs) { console.log(x); } Detailed examples are below. 1. Sequential for loop: var myStringArray = [“Hello”,”World”]; var arrayLength = myStringArray.length; for (var i = 0; i < arrayLength; i++) { console.log(myStringArray[i]); //Do … Read more