The differences between var, let, and const variable declaration in JavaScript include: Variables declared with var and const are scoped to the immediate function body. Variables declared with the var keyword are hoisted. Hoisting means that the variable can be accessed in their enclosing scope even before they are declared. Variables declared with the let keyword are block-scoped, which means the variables will have scope to the immediate enclosing block.
1. Regular function
Inside of a regular JavaScript function, this value (aka the execution context) is dynamic.
The dynamic context means that the value of this depends on how the function is invoked. In
JavaScript,
there are 4 ways you can invoke a regular function.
2. The behavior of this inside of an arrow function differs considerably from the regular function's
this
behavior. The arrow function doesn't define its own execution context.
No matter how or where being executed, this value inside of an arrow function always equals this
value
from
the outer function. In other words, the arrow function resolves this lexically.
Template literals are sometimes informally called template strings, because they are used most commonly for string interpolation (to create strings by doing substitution of placeholders). However, a tagged template literal may not result in a string; it can be used with a custom tag function to perform whatever operations you want on the different parts of the template literal.
The main difference between forEach and filter is that forEach just loop over the array and executes the callback but filter executes the callback and check its return value. If the value is true element remains in the resulting array but if the return value is false the element will be removed for the resulting array.