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Categories / JavaScript Tutorial / Operators
 

Assignment by Value Versus by Reference

When the assignment operator works on primitive values (numbers, strings, Boolean, null, and undefined), a copy of the value is made. When the assignment operator works on JavaScript objects, references to the objects are copied. <html> <SCRIPT LANGUAGE="JavaScript"> <!--     var number1 = 9;     var arrayOfNum1 = new Array(2,6);     var number2 = number1;     var arrayOfNum2 = arrayOfNum1;     number2 = 2;     arrayOfNum2[1] = 4;     document.write("number1=",number1,"<BR>");     document.write("number2=",number2,"<BR>");     document.write("arrayOfNum1[0]=",arrayOfNum1[0],"<BR>");     document.write("arrayOfNum1[1]=",arrayOfNum1[1],"<BR>");     document.write("arrayOfNum2[0]=",arrayOfNum2[0],"<BR>");     document.write("arrayOfNum2[1]=",arrayOfNum2[1],"<BR>"); --> </SCRIPT> </html>