[javascript allows the use of variables that have not yet been declared and allows variables to be declared after they were first used. For example, the following syntax is legal:
x = 123;
console.log("number is ", 123);
var x;Hoisting is a behaviour where the javascript engine will move declarations to the top of the current scope so the above code would be interpreted as:
var x;
x = 123;
console.log("number is ", 123);Function Hoisting
Function definitions/declarations are also hoisted such that they can be called before they have been defined as in the following example:
foo();
function foo() {
alert("Hello!");
}However,