Top 12 Lesser Known Tips for JavaScript Best Practices

Top 12 Lesser Known Tips for JavaScript Best Practices

There is a lot of information about different JS features. I want to tell you about equally useful, but less popular tips for working with this language!

Hi everyone! There is a lot of information about different JS best practices. About various life hacks and features in this language. I want to tell you about equally useful, but less popular tips for working with this JavaScript.

1. Variables declared with "var" should be declared before they are used

Variables declared with 

var have the special property that regardless of where they're declared in a function they "float" to the top of the function and are available for use even before they're declared. That makes scoping confusing, especially for new coders.

To keep confusion to a minimum, 

var declarations should happen before they are used for the first time.

Bad example:

var x = 1;

function fun(){
  alert(x); // Noncompliant as x is declared later in the same scope
  if(something) {
    var x = 42; // Declaration in function scope (not block scope!) shadows global variable
  }
}

fun(); // Unexpectedly alerts "undefined" instead of "1"

Good example:

var x = 1;

function fun() {
  print(x);
  if (something) {
    x = 42;
  }
}

fun(); // Print "1"

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