JavaScript: Block statement

Last update on May 28 2022 10:19:24 (UTC/GMT +8 hours)

Description

Block statements are commonly used with control flow statements i.e. while, for, if etc. The block is delimited by a pair of curly brackets.

Syntax

{ 
statement_1 
statement_2
 .    .    . 
statement_n 
}

Parameters

statement_1, statement_2, .... , statement_n

Where statements are grouped within the block statement.

Example:

 if x>10
  {
  y=12
  z=20
  }
  or while ( roll_no <= 40 )
  {
  roll_no++
  }

JavaScript does not support block scope. In the following example output of the variable a will be 1 because var a statement within or before condition have same scope whereas in Java or C language the output of the same code will be 101.

var a = 101
  {
  a = 1;
  }
  console.log(a) 
  //output 1

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JavaScript: Tips of the Day

How to insert an item into an array at a specific index (JavaScript)?

What you want is the splice function on the native array object.

arr.splice(index, 0, item); will insert item into arr at the specified index (deleting 0 items first, that is, it's just an insert). In this example we will create an array and add an element to it into index 2:

var arr = [];
arr[0] = "Jani";
arr[1] = "Hege";
arr[2] = "Stale";
arr[3] = "Kai Jim";
arr[4] = "Borge";

console.log(arr.join());
arr.splice(2, 0, "Lene");
console.log(arr.join());

Ref: https://bit.ly/2BXbp04