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**JAVASCRIPT BASICS**
*Rev 4: December 2004*

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TABLE OF CONTENTS4. JavaScript Comparison Operators:
The JavaScript Comparison Operators allow programmers to test for more subtle conditions than the simple existence of an object (relative equality, inequality, etc.)
The operators are included in the statement of conditions using the following general syntax if(value1 operator value2) { [statements];} The values compared in the test (value1, value2) can be either variables, literal values and/or the result of one or more operations. if(x operator 1) { [statements];} if(x operator "one") { [statements];} if(x operator y) { [statements];} if(x operator (y-1)) { [statements];} The examples below demonstrate the behaviors and basic syntax for each of the operators. Note that the examples assume the existence of variable (x) that is assigned a value of 1 (var x=1):
The Equality Operator (x==y) returns true if x is equal to y, else false. In this example the value of x is equal to one (1) so the comparison returns true:
Listing 4.1 Equality
var x = 1; if(x==1) {document.write("Condition True"); } else { document.write("Condition False"); }
Condition True
Note that the equality operator is two equal signs (==), and that using a single equal sign will result assigning rather than testing the values compared.
The Inequality Operator (x != y) returns true if x is not equal to y, else false. In this example the value of x is equal to one (1) so the comparison returns false:
Listing 4.2 Inequality
var x = 1; if(x!=1) {document.write("Condition True") } else { document.write("Condition False"); }
Condition False
The Greater Than Operator (x > y) returns true if x is greater than y, else false. In this example the value of x is not greater than one (1) so the comparison returns false:
Listing 4.3 Greater Than
var x = 1; if(x>1) {document.write("Condition True"); } else { document.write("Condition False"); }
Condition False
The Greater Than/Equal To Operator (x >= y) returns true if x is greater than or equal to y, else false. In this example the value of x is not less than but is equal to one (1) so the comparison returns true:
Listing 4.4 Greater Than/Equal To
var x = 1; if(x>=1) {document.write("Condition True"); } else { document.write("Condition False"); }
Condition True
The Less Than Operator (x < y) returns true if x is less than y, else false. In this example the value of x is not less than one (1) so the comparison returns false:
Listing 4.5 Less Than
var x = 1; if(x<1) {document.write("Condition True"); } else { document.write("Condition False"); }
Condition False
The Less Than/Equal To Operator (x <= y) returns true if x is less than or equal to y. In this example the value of x is not less than but is equal to one (1) so the comparison returns true:
Listing 4.6 Less Than/Equal To
var x = 1; if(x<=1) {document.write("Condition True"); } else { document.write("Condition False"); }
Condition True
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