Learning JavaScript tutorial – JavaScript with Statement

JavaScript offer lots of verity whiling dealing with the statements. Along with the flow control and loop control statements JavaScript supports object-related "with statements". With statement allows using a shorthand notation when referring objects and deals with the object scope chain.

with (object)
{
  statement(s);
}

Let us consider an example of the document object allows us to access the objects that compose a document. Using JavaScript with Statement we can access the scope of document object.

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Learning JavaScript tutorial – JavaScript switch Statement

JavaScript switch statement control the flow of program execution via a multiway branch. When we need execute a statement block depending on the value of a single variable; JavaScript switch Statement is the best alternative to JavaScript if Condition Statement to it handles the situation more efficiently than repeated if statements.

JavaScript switch Statement Syntax

switch (conditional expression)
{
  case condition 1:
    statement block executed if condition 1 is true(satisfied).
        break;
  case condition 2:
    statement block executed if condition 1 is true(satisfied).
        break;
  .
  .
  .
  case condition n:
    statement block executed if condition n is true(satisfied).
        break;
  default:
    statement block executed if no condition is true(satisfied).
    break;
}

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Learning JavaScript tutorial – JavaScript if, if else and else if Condition Statement

Decision making based on different computations or perform actions depending on a programmer-specified condition is one of the features of the JavaScript language.

JavaScript if Condition Statement

JavaScript if Condition Statements are used to perform different actions (make decisions) based on different conditions evaluated to a Boolean true or false. JavaScript if Condition Statement help us to execute statement block conditionally.

JavaScript if Condition Statement Syntax

if (conditional expression)
  {
  statement block executed if condition is true(satisfied).
  }

Here, If the resulting value of conditional expression is true or can be evaluated to true, statement block enclosed within the Curly braces – {} is executed.

If Condition Statement flowchart

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Learning JavaScript tutorial – JavaScript Statements

A JavaScript program is simply a sequence of one or more JavaScript statements. JavaScript Statements is used to define the logic to make something happen. A statement can be used to declare a variable and assign a value. A statement can also be a function call, i.e. document.write(). JavaScript Statements are separated from each other with semicolons. The semicolon is optional in JavaScript, if you place each JavaScript statement on a separate line, JavaScript allows us to leave out the semicolons. The best practice of defining JavaScript Statements is to use semicolons, everywhere at the end of the each JavaScript statement.

JavaScript Statement Blocks

JavaScript Statement Block use Curly braces – {} to group a series of JavaScript Statements together to perform some sort of operation repeatedly or once based on desire condition. Whenever a JavaScript Statement Block occurs in JavaScript program is treated as a single statement. JavaScript Statement Block plays an important role while dealing with Conditional and Loop Statements.

<script type="text/javascript">
var iCount=0;
var iSum=0;
while(iCount<=5){
 iSum=iSum+iCount;
 iCount++;
}
alert(iSum); //alert 15
</script>

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Learning JavaScript tutorial – JavaScript Operator Precedence and Associativity

In our last article "Learning JavaScript tutorial – JavaScript Expressions and Operators", we take a look at JavaScript Operators. JavaScript Operators have a predefined order of precedence which are used to process and evaluate a JavaScript expression. JavaScript Operator Precedence is similar to the Mathematical Operator Precedence and Associativity. Like basic algebra Operator Precedence, JavaScript multiplication and division Operator have higher precedence over addition and subtraction Operator. For example:

alert(4 + 3 * 2);  // alert ’10′

Using parentheses, we can group expressions so that we can evaluate any JavaScript expressions in an order of our choice. For example:

alert(4 + 3 * 2);  // alert ’10′
alert((4 + 3) * 2); // alert ’14′
alert((4 / 2) * 2); // alert ’4′

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