Flattening an array means to take an array of nested arrays, ie a multidimensional array, and reduce it to a single dimension array. arr1.flat(2) The flat method takes as an argument the depth of dimensions which need to be flattened.

A weakmap is a collection of key value pairs, in which the key must always be an object. A WeakMap is a map (dictionary) where the keys are weak - that is, if all references to the key are lost and there are no more references to the value - the value can be garbage collected.

Cross site scripting.

A semantic element clearly describes its meaning to the browser and the developer. Header, footer, nav, aside, section, main, article, table. Non semantic - div, span, What is the box model? A web browser renders elements as a rectangular box. The size of this box depends on the css properties of its content, such as the content itself, the margin, border and padding.

Customer relationship management software

The ‘this’ keyword refers to the object that the function is a property of. function dosomething() { console.log(this) // window object in a browser } dosomething(); In the above example the function is a property of the window object ie the global object. When a function is invoked, the object before the dot is the value of this. If there is no object before the dot, the value is the global object.

Inheritance is a way to reuse existing code. A derived class inherits from a base class, such that the derived class will have access to the base classes attributes and methods.

A predicate function is a function which returns a boolean, either True or False.