5 Minute JavaScript #3 var-statement

In our previous post we discussed the importance of functions and scopes. The var-statement is narrowly linked to these concepts. Most Object-Oriented languages are statically typed. This means that you will need to declare the type of the variable you want to define before compiling. JavaScript however is dynamically typed and every value is defined with a var-statement.

var number = 1;
number = "Now it’s a string";

If the type of a variable can change, it gets tricky. You should never do that, but JavaScript allows it.

Back to the var statement. Using this statement is just like saying “name this value and bind it to the nearest scope”. An example:

function f () {
    var variable = "value";

The var-statement will make the “value” with the name ‘variable’ accessible in the context (scope) of the function f (because this is the first scope it encounters).

It’s important to know that only functions can create scopes. So, visibility of a variable will only be bound to a function. This means that functions become increasingly more important in JavaScript. Check out our previous blog post if you want to know a little more about functions and scopes.

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