JavaScript DHTML/Language Basics/Operator — различия между версиями

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Текущая версия на 07:24, 26 мая 2010

Add two integer variables together

  
<html>
<head>
<title>A Simple Page</title>
<script language="JavaScript">
var a = 6, b = 4; 
alert(a + b);
</script>
</head>
<body>
</body>
</html>



Examples of Increment and Decrement Operators

  
<html>
<head>
  <title>JavaScript Unleashed</title>
</head>
<body>
   
  <script type="text/javaScript">
  <!--
    var i = 0;  
    var result = 0
   
    document.write("If i = 0, ");
    document.write("i returns the value of i");
    document.write(" after incrementing  : ");
   
    // Increment prefix
    result = ++i; 
   
    document.write(result);
    i = 0; 
    document.write("<br>i++ returns the value of i");
    document.write(" before incrementing : ");
   
    // Increment suffix
    result = i++; 
    document.write(result);
    i = 0; 
    document.write("<br>--i returns the value of i");
    document.write(" after decrementing  : ");
   
    // Decrement prefix
    result = --i; 
    document.write(result)
   
    i = 0;
    document.write("<br>i-- returns the value of i");
    document.write(" before decrementing : ");
       // Decrement suffix
    result = i--;
   
    document.write(result);
    // -->
  </script>
   
</body>
</html>



JavaScript compound divide assignment

  
<html>
<head>
<title>A Simple Page</title>
<script language="JavaScript">
var x = 6; 
alert(x /= 2);
</script>
</head>
<body>
</body>
</html>



JavaScript compound multiply assignment

  
<html>
<head>
<title>A Simple Page</title>
<script language="JavaScript">
var x = 6; 
alert(x *= 2);
</script>
</head>
<body>
</body>
</html>



JavaScript compound plus assignment

  

<html>
<head>
<title>A Simple Page</title>
<script language="JavaScript">
var x = 6; 
alert(x += 2);
</script>
</head>
<body>
</body>
</html>



JavaScript compound subtraction assignment

  
<html>
<head>
<title>A Simple Page</title>
<script language="JavaScript">
var x = 6; 
alert(x -= 2);
</script>
</head>
<body>
</body>
</html>



Modular operation (remainder in division)

  
<html>
<head>
<title>A Simple Page</title>
<script language="JavaScript">
var a = 6, b = 4; 
alert(a % b);
</script>
</head>
<body>
</body>
</html>



Multiply two integer variables together

  
<html>
<head>
<title>A Simple Page</title>
<script language="JavaScript">
var a = 6, b = 3; 
alert(a * b);
</script>
</head>
<body>
</body>
</html>



Operators and Expressions:Operator Summary Table

  
<html>
<head>
<title>JavaScript Operators</title>
</head>
<body>
<h1>JavaScript Operators</h1>
<table BORDER="2" CELLPADDING="4" ALIGN="CENTER">
<tr><td>Category</td>
<td>Operator</td>
<td>Description</td>
<td>Usage Example</td>
<td>Value/Result</td></tr>
<tr><td>String</td>
<td>+</td>
<td>concatenation</td>
<td>&quot;Java&quot; + &quot;Script&quot;</td>
<td><script><!--
document.write("Java"+"Script")
// --></script>
</td></tr>
<tr><td ROWSPAN="10">Arithmetic</td>
<td>+</td>
<td>addition</td>
<td>3 + 3</td>
<td><script><!--
document.write(3+3)
// --></script>
</td></tr>
<tr><td ROWSPAN="2">-</td>
<td>subtraction</td>
<td>6 - 2</td>
<td><script><!--
document.write(6-2)
// --></script>
</td></tr>
<tr><td>unary negation</td>
<td>-4</td>
<td><script><!--
document.write(-4)
// --></script>
</td></tr>
<tr><td>*</td>
<td>multiplication</td>
<td>4 * 4</td>
<td><script><!--
document.write(4*4)
// --></script>
</td></tr>
<tr><td>/</td>
<td>division</td>
<td>15/5</td>
<td><script><!--
document.write(15/5)
// --></script>
</td></tr>
<tr><td>%</td>
<td>modulus</td>
<td>22%7</td>
<td><script><!--
document.write(22%7)
// --></script>
</td></tr>
<tr><td ROWSPAN="2">++</td>
<td>increment and then return value</td>
<td>x=4; ++x</td>
<td><script><!--
x=4
document.write(++x)
// --></script>
</td></tr>
<tr><td>return value and then increment</td>
<td>x=4; x++</td>
<td><script><!--
x=4
document.write(x++)
// --></script>
</td></tr>
<tr><td ROWSPAN="2">--</td>
<td>decrement and then return value</td>
<td>x=3; --x</td>
<td><script><!--
x=3
document.write(--x)
// --></script>
</td></tr>
<tr><td>return value and then decrement</td>
<td>x=4; x--</td>
<td><script><!--
x=4
document.write(x--)
// --></script>
</td></tr>
<tr><td ROWSPAN="6">Bit Manipulation</td>
<td>&amp;</td>
<td>and</td>
<td>11 &amp; 7</td>
<td><script><!--
document.write(11&7)
// --></script>
</td></tr>
<tr><td>|</td>
<td>or</td>
<td>8 | 7</td>
<td><script><!--
document.write(8|7)
// --></script>
</td></tr>
<tr><td>^</td>
<td>exclusive or</td>
<td>1 ^ 7</td>
<td><script><!--
document.write(1^7)
// --></script>
</td></tr>
<tr><td>&lt;&lt;</td>
<td>left shift</td>
<td>8 &lt;&lt; 3</td>
<td><script><!--
document.write(8 << 3)
// --></script>
</td></tr>
<tr><td>&gt;&gt;</td>
<td>sign-propagating right shift</td>
<td>-3 &gt;&gt; 2</td>
<td><script><!--
document.write(-3 >> 2)
// --></script>
</td></tr>
<tr><td>&gt;&gt;&gt;</td>
<td>zero-fill right shift</td>
<td>-7 &gt;&gt;&gt; 3</td>
<td><script><!--
document.write(-7>>>3)
// --></script>
</td></tr>
<tr><td ROWSPAN="3">Logical</td>
<td>&amp;&amp;</td>
<td>logical and</td>
<td>true &amp;&amp; false</td>
<td><script><!--
document.write(true&&false)
// --></script>
</td></tr>
<tr><td>||</td>
<td>logical or</td>
<td>true || false</td>
<td><script><!--
document.write(true||false)
// --></script>
</td></tr>
<tr><td>!</td>
<td>not</td>
<td>!true</td>
<td><script><!--
document.write(!true)
// --></script>
</td></tr>
<tr><td ROWSPAN="6">Comparison</td>
<td>==</td>
<td>equal</td>
<td>3 == 7</td>
<td><script><!--
document.write(3==7)
// --></script>
</td></tr>
<tr><td>!=</td>
<td>not equal</td>
<td>3 != 7</td>
<td><script><!--
document.write(3!=7)
// --></script>
</td></tr>
<tr><td>&lt;</td>
<td>less than</td>
<td>3 &lt; 7</td>
<td><script><!--
document.write(3<7)
// --></script>
</td></tr>
<tr><td>&lt;=</td>
<td>less than or equal</td>
<td>3 &lt;= 7</td>
<td><script><!--
document.write(3<=7)
// --></script>
</td></tr>
<tr><td>&gt;</td>
<td>greater than</td>
<td>3 &gt; 7</td>
<td><script><!--
document.write(3>7)
// --></script>
</td></tr>
<tr><td>&gt;=</td>
<td>greater than or equal</td>
<td>3 &gt;= 7</td>
<td><script><!--
document.write(3>7)
// --></script>
</td></tr>
<tr><td>Conditional Expression</td>
<td>(condition) ? value1 : value2</td>
<td>if condition is true then value1 else value2</td>
<td>true ? 3 : 7</td>
<td><script><!--
document.write(true?3:7)
// --></script>
</td></tr>
</table>
</body>
</html>



Postfix adding

  

<html>
<head>
<title>A Simple Page</title>
<script language="JavaScript">
var a = 6, b = 2; 
alert(a++ + b);
alert(a);
</script>
</head>
<body>
</body>
</html>



Postfix operator for integer

 

<html>
<head>
<title></title>
</head>
<body>
<script type="text/javascript">
var theNum = 1;
document.write(theNum+"<BR>");
document.write(theNum++);

</script>
</body>
</html>



Postfix subtraction

  
<html>
<head>
<title>A Simple Page</title>
<script language="JavaScript">
var a = 6, b = 2; 
alert(a-- + b);
alert(a);
</script>
</head>
<body>
</body>
</html>



Prefix operator for integer

 
<html>
<head>
<title></title>
</head>
<body>
<script type="text/javascript">
var theNum = 1;
document.write(theNum+"<BR>");
document.write(++theNum+"<BR>");
document.write(theNum+"<BR>");
</script>
</body>
</html>



Prefix plus

  
<html>
<head>
<title>A Simple Page</title>
<script language="JavaScript">
var a = 6, b = 2; 
alert(++a + b);
</script>
</head>
<body>
</body>
</html>



Prefix subtraction

  
<html>
<head>
<title>A Simple Page</title>
<script language="JavaScript">
var a = 6, b = 2; 
alert(--a + b);
</script>
</head>
<body>
</body>
</html>



Subtract one integer variable from another integer variable

  
<html>
<head>
<title>A Simple Page</title>
<script language="JavaScript">
var a = 6, b = 4; 
alert(a - b);
</script>
</head>
<body>
</body>
</html>



Tenary operator

 

<html>
<head>
<title></title>
</head>
<body>
<script type="text/javascript">
var temp = prompt("Number");
temp > 100 ? alert("> 100") : alert("< 100");
</script>
</body>
</html>



Ternary operator

  
<html>
<head>
<title>A Simple Page</title>
<script language="JavaScript">
var w = 1, x = 2, y = 3, z = 4, ans; 
ans = (w > x) ? y : z
alert(ans);
</script>
</head>
<body>
</body>
</html>



Using the Equal Operator

  
<html>
<head>
  <title>Using the Equal Operator</title>
</head>
<body>  <script type="text/javascript">
  <!--
    var x = 5;
    var y = 5;
    var z = 10;
    document.write("x = " + x + "<br>");
    document.write("y = " + y + "<br>");
    document.write("z = " + z + "<br>");
    document.write("Is x equal to y,(x == y)? ");
    document.write(x == y);
    document.write("<br>Is y equal to z,(y == z)? ");
    document.writeln(y == z);
  // -->
  </script>
   
</body>
</html>



Working with the Increment Operator

  
<HTML>
<BODY>
<H1>
<SCRIPT> 
var Inc = 1; 
document.write("Starting value of " + Inc + "<BR>"); 
document.write("IncPreFix " + ++Inc + "<BR>"); 
document.write("IncPostFix " + Inc++ + "<BR>"); 
document.write("Ending value of " + Inc); 
</script>
</H1>
</BODY>
</HTML>
Источник — «http://wbex.ru/index.php?title=JavaScript_DHTML/Language_Basics/Operator&oldid=3109»