Conditional statements in JavaScript are used to perform different actions based on different conditions.
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Examples
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Switch statement[¿ª¹ØÓï¾ä]
How to write a switch statement.
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The JavaScript Switch Statement
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You should use the switch statement if you want to select one of many blocks of code to be executed.
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Syntax
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switch(n)
{
case 1:
  execute code block 1
  break    
case 2:
  execute code block 2
  break
default:

  code to be executed if n is
  different from case 1 and 2
}

This is how it works: First we have a single expression n (most often a variable), that is evaluated once. The value of the expression is then compared with the values for each case in the structure. If there is a match, the block of code associated with that case is executed. Use break to prevent the code from running into the next case automatically.
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Example
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<script type="text/javascript">
//You will receive a different greeting based
//on what day it is. Note that Sunday=0,
//Monday=1, Tuesday=2, etc.

var d=new Date()
theDay=d.getDay()
switch (theDay)
{
case 5:
  document.write("Finally Friday")
  break
case 6:
  document.write("Super Saturday")
  break
case 0:
  document.write("Sleepy Sunday")
  break
default:
  document.write("I'm looking forward to this weekend!")
}

</script>

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