[Javascript] Top Javascript Tips and Tricks

In this post, We will discuss some of the tips and tricks that every javascript developer must know.

Boolean Expression

• null, undefined, ‘ ‘ the empty string and 0 the number are all false boolean expression.
• But be careful, ‘0’ the string, [ ] the empty array, and {} the empty object are all true boolean expression.

so instead of using

if(x != null)

You can write the shorter format

if(x)

Similarly, if you want to check both null and empty. You can do like this:

if(x != null && x != ‘ ‘)

However, You can write short and nice

if(x)

Conditional Ternary Operator

Instead of this,

if (x) {
foo();
} else {
bar();
}

you can use the ternary operator,

return x ? foo( ) :bar( )

Short Circuit Operator

&& and ||, these operators are called as short circuit operators. Consider the following code.

function foo(x) {
var win;
if (x) {
win = x;
} else {
win = window;
}
}

You can rewrite above code as

function foo(x) {
  var win = x || window;
}

&& is also used to reduce the lines of code, Please find the code below.

if (student) {
  if (student.name) {
    if (student.name[index]) {
      foo(student.name[index]);
    }
  }
}

You can rewrite the code as

if (student && student.name && student.name[index]) {
  foo(student.name[index]);
}

or, you can use a variable as,

var flag = student && student.name && student.name[index];
if (flag) {
  foo(student.name[index]);
}

Iteration using for loop:

For loop:

var paragraphs = [1, 2, 3, 4, 5, 6];
for (var i = 0; i < paragraphs.length; i++) {
  var paragraph = paragraphs[i];  
  console.log(paragraph);
}

Above code can be modified as below.

var paragraphs = [1, 2, 3, 4, 5, 6];
for (var i = 0, paragraph; paragraph = paragraphs[i]; i++) {
  console.log(paragraph);
}

Next Article: [Angular] Quick Jump from AngularJS to Angular

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