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JavaScript Tutorial/Operators/Arithmetic operator - История изменений
2026-04-04T11:32:39Z
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Admin: 1 версия
2010-05-26T08:24:51Z
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Admin
http://wbex.ru/index.php?title=JavaScript_Tutorial/Operators/Arithmetic_operator&diff=9160&oldid=prev
в 18:52, 25 мая 2010
2010-05-25T18:52:56Z
<p></p>
<p><b>Новая страница</b></p><div>== += (Addition Assignment)==<br />
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<p>Syntax</p><br />
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<!-- start source code --><br />
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<source lang="javascript"><br />
variable += value</source><br />
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== + (Addition) with data type conversion==<br />
<br />
<br />
<br />
<br />
<!-- start source code --><br />
<br />
<source lang="javascript"><br />
<html><br />
<script language="JavaScript"><br />
<!--<br />
aString = new String("67");<br />
answerNum = 67 + 23;<br />
answerStr = aString + 23;<br />
document.write("answerNum =",answerNum,"<br>");<br />
document.write("answerStr =",answerStr);<br />
--><br />
</script><br />
</html></source><br />
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== Add string and integer together==<br />
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<br />
<!-- start source code --><br />
<br />
<source lang="javascript"><br />
<html><br />
<head><br />
<title>A Simple Page</title><br />
<script language="JavaScript"><br />
<!--<br />
var A = "10", B = 5;<br />
C = A + B;<br />
alert(C);<br />
// --><br />
</script><br />
</head><br />
<body><br />
</body><br />
</html></source><br />
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== Append two strings together==<br />
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<br />
<br />
<!-- start source code --><br />
<br />
<source lang="javascript"><br />
<html><br />
<head><br />
<title>A Simple Page</title><br />
<script language="JavaScript"><br />
<!--<br />
var A = "JavaScript ", B = "by Example!";<br />
C = A + B;<br />
alert(C);<br />
// --><br />
</script><br />
</head><br />
<body><br />
</body><br />
</html></source><br />
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<br />
<br />
== Arithmetic operator in action==<br />
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<br />
<br />
<!-- start source code --><br />
<br />
<source lang="javascript"><br />
<html><br />
<head><br />
<title>A Simple Page</title><br />
<script language="JavaScript"><br />
<!--<br />
var a = 6, b = 3;<br />
alert(a * b);<br />
// --><br />
</script><br />
</head><br />
<body><br />
</body><br />
</html></source><br />
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<br />
== Arithmetic Operators (+)==<br />
<br />
<p>All the common arithmetic operators will attempt to convert strings to numbers when applicable.</p><br />
<p>If a string cannot be converted to a number, NaN (Not A Number) will be returned.</p><br />
<p>Addition (+)</p><br />
<p>If the values on either side are numerical values, the values are added together.</p><br />
<p>IF the values are strings, they are concatenated together.</p><br />
<p>The following line of code</p><br />
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<!-- start source code --><br />
<br />
<source lang="javascript"><br />
var resultOfAdd = 34 + 12;</source><br />
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== Compound assignment operators==<br />
<br />
<p>Compound assignment operators exist for each of the major mathematical operations and a few others as well:</p><br />
<p>Multiply/Assign (*=)</p><br />
<p>Divide/Assign (/=)</p><br />
<p>Modulus/Assign (%=)</p><br />
<p>Add/Assign (+=)</p><br />
<p>Subtract/Assign (-=)</p><br />
<p>Left Shift/Assign (<<=)</p><br />
<p>Signed Right Shift/Assign (>>=)</p><br />
<p>Unsigned Right Shift/Assign (>>>=)</p><br />
2. 1. Arithmetic operator<br />
2. 1. 1. <br />
Compound assignment operators<br />
2. 1. 2. <br />
<A href="/Tutorial/JavaScript/0040__Operators/ArithmeticOperators.htm">Arithmetic Operators (+)</a><br />
2. 1. 3. <br />
<A href="/Tutorial/JavaScript/0040__Operators/Appendtwostringstogether.htm">Append two strings together</a><br />
2. 1. 4. <br />
<A href="/Tutorial/JavaScript/0040__Operators/Addstringandintegertogether.htm">Add string and integer together</a><br />
2. 1. 5. <br />
<A href="/Tutorial/JavaScript/0040__Operators/Additionwithdatatypeconversion.htm">+ (Addition) with data type conversion</a><br />
2. 1. 6. <br />
<A href="/Tutorial/JavaScript/0040__Operators/AdditionAssignment.htm">+= (Addition Assignment)</a><br />
2. 1. 7. <br />
<A href="/Tutorial/JavaScript/0040__Operators/Subtraction.htm">Subtraction (-)</a><br />
2. 1. 8. <br />
<A href="/Tutorial/JavaScript/0040__Operators/Multiplication.htm">Multiplication (*)</a><br />
2. 1. 9. <br />
<A href="/Tutorial/JavaScript/0040__Operators/MultiplicationAssignment.htm">*= (Multiplication Assignment)</a><br />
2. 1. 10. <br />
<A href="/Tutorial/JavaScript/0040__Operators/Division.htm">Division (/)</a><br />
2. 1. 11. <br />
<A href="/Tutorial/JavaScript/0040__Operators/WorkingWithJavaScriptDivideOperators.htm">Working With JavaScript Divide Operators</a><br />
2. 1. 12. <br />
<A href="/Tutorial/JavaScript/0040__Operators/DivisionAssignment.htm">/= (Division Assignment)</a><br />
2. 1. 13. <br />
<A href="/Tutorial/JavaScript/0040__Operators/Arithmeticoperatorinaction.htm">Arithmetic operator in action</a><br />
2. 1. 14. <br />
<A href="/Tutorial/JavaScript/0040__Operators/UnaryNegation.htm">Unary Negation</a><br />
2. 1. 15. <br />
<A href="/Tutorial/JavaScript/0040__Operators/Stringandadditionoperator.htm">String and addition operator (+)</a><br />
<br />
== Division (/)==<br />
<br />
<p>If either of the operands is a string, an attempt is made to convert the string to a number.</p><br />
<p>For example, the following line of code</p><br />
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<source lang="javascript"><br />
var resultOfDiv = 42 / 7;</source><br />
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== /= (Division Assignment)==<br />
<br />
Syntax<br />
variable /= value<br />
<br />
<br />
<br />
<!-- start source code --><br />
<br />
<source lang="javascript"><br />
<html><br />
<script language="JavaScript"><br />
<!--<br />
x = 32;<br />
aString = new String("8");<br />
x /= aString;<br />
document.write("x = ",x);<br />
--><br />
</script><br />
</html></source><br />
<br />
<br />
<br />
== Multiplication (*)==<br />
<br />
<p>The multiplication operator (*) multiplies the left operand by the right operand.</p><br />
<p>When either of the operands are strings, an attempt is made to convert the strings to numbers.</p><br />
<p>For example, the following line of code</p><br />
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<br />
<!-- start source code --><br />
<br />
<source lang="javascript"><br />
var resultOfMult = 5 * 7;</source><br />
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== *= (Multiplication Assignment)==<br />
<br />
<br />
<br />
<br />
<!-- start source code --><br />
<br />
<source lang="javascript"><br />
<html><br />
<script language="JavaScript"><br />
<!--<br />
x = 7;<br />
aString = new String("5");<br />
x *= aString;<br />
document.write("x = ",x);<br />
--><br />
</script><br />
</html></source><br />
<br />
<br />
<br />
== String and addition operator (+)==<br />
<br />
<p>If the values on either side of the addition operator are strings, the strings are concatenated together.</p><br />
<p>If only one of the values is a string, the other value is converted to a string and concatenated with the first value.</p><br />
<br />
<br />
<br />
<!-- start source code --><br />
<br />
<source lang="javascript"><br />
<html><br />
<SCRIPT LANGUAGE="JavaScript"><br />
<!--<br />
var sStringVar1 = "Hello";<br />
var sStringVar2 = "World";<br />
var nNumVar1 = 5;<br />
var nNumVar2 = 10;<br />
var sStringTotal = sStringVar1 + sStringVar2;<br />
var nNumTotal = nNumVar1 + nNumVar2;<br />
var sStringNumTotal = sStringTotal + nNumTotal;<br />
<br />
document.write("<b>The string total is: </b>"+sStringTotal+"<BR>");<br />
document.write("<b>The numeric total is: </b>",nNumTotal,"<BR>");<br />
document.write("<b>The string + numeric total is: </b>",sStringNumTotal);<br />
--><br />
</SCRIPT><br />
</html></source><br />
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<br />
<br />
== Subtraction (-)==<br />
<br />
<p>The subtraction operator (-) subtracts the number to the right of the operator from the number on the left.</p><br />
<p>When either of the operands are strings, an attempt is made to convert the strings to numbers.</p><br />
<p>For example, the line of code:</p><br />
<br />
<br />
<br />
<!-- start source code --><br />
<br />
<source lang="javascript"><br />
var resultOfSub = 25 - 102;</source><br />
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== Unary Negation==<br />
<br />
<p>If the value is a string, an attempt is made to convert the string to a number.</p><br />
<br />
<br />
<br />
<!-- start source code --><br />
<br />
<source lang="javascript"><br />
<html><br />
<script language="JavaScript"><br />
<!--<br />
aString = new String("36");<br />
answer = -aString;<br />
document.write("answer = -aString<br>");<br />
document.write("answer = ",answer);<br />
--><br />
</script><br />
</html></source><br />
<br />
<br />
<br />
== Working With JavaScript Divide Operators==<br />
<br />
<br />
<br />
<br />
<!-- start source code --><br />
<br />
<source lang="javascript"><br />
<HTML><br />
<HEAD><br />
<TITLE><br />
Working With JavaScript Operators<br />
</TITLE><br />
</HEAD><br />
<BODY><br />
<H1>Working With JavaScript Operators</H1><br />
<SCRIPT LANGUAGE="JavaScript"><br />
<!--<br />
var pounds = 2.0<br />
var kilograms = pounds / 2.2046<br />
document.write(pounds + " pounds is the same as " + kilograms.toPrecision(4) + " kilograms.")<br />
// --><br />
</SCRIPT><br />
</BODY><br />
</HTML></source></div>