The main problem with Remove all but numbers is that it removes all text, including any formatting, from a document. This can make it difficult to read and potentially damaging to the data if it is not properly cleaned up.
from a string var str = "abc123"; var newStr = str.replace(/[^0-9]/g, "");
This code is taking the string “abc123” and using a regular expression to replace any character that is not a number with an empty string. So the end result is the string “123”.
Classes
There are many different types of classes in JavaScript. They can be divided into two main categories: object-oriented and functional.
Object-oriented classes are built around the concept of objects. An object is a collection of properties and methods that can be accessed using the dot operator. For example, the following code creates an object called person that has a property called name and a method called sayName() :
var person = { name: “John”, sayName: function() { console.log(“Hello, my name is ” + this.name); } };
Functional classes are built around the concept of functions. A function is a block of code that can be executed by calling it with one or more arguments. For example, the following code creates a function called addNumbers() that takes two arguments, x and y :
function addNumbers(x, y) { return x + y; }
Both object-oriented and functional classes can contain properties and methods, but they differ in how they handle inheritance. In object-oriented classes, inheritance means that you can create new objects that are based on existing objects by using the extends keyword. For example, you could create a new person object by extending the person object shown above:
var newPerson = Object.create(person); newPerson.name = “Mary”;
Arguments
Arguments in JavaScript are always passed by value. This means that the arguments are copied when they are passed to a function. This can be a problem if you want to pass a reference to an argument.
For example, consider the following code:
function add(a, b) { return a + b; }
If you call add with two arguments, the first argument will be assigned to the first variable and the second argument will be assigned to the second variable. However, if you want to pass a reference to an argument, you need to use a different approach:
function add(ref A, ref B) { return A + B; }
