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Table 5.6 Comparison Operators (continued)
Operator/Operands
Function
x >= y
x is greater than or equal to y
x < y
x is less than y
x <= y
x is less than or equal to y
x = = = y
x is identical to y in value and type
x != = y
x is not identical to y
What Is Equal? In an id l wo ld, th e would be equ y b tw en the ex s and
among the races and religions, but in the real world equality is a debatable topic, often
determined by governments. In JavaScript, operators determine the equality or inequal-
ity of their operands, based on more specific rules. When using the == or != equality
operators, the operands may be of any given data type—numbers, strings, Booleans,
objects, arrays, or a combination of these—and there are rules that govern whether they
are equal. For example, two strings are equal when they have the same sequence of char-
acters, same length, and same characters in corresponding positions. Two numbers are
equal when they have the same numeric value. If a string is compared with a number,
they are equal if the number has the same characters as the string; for example, “500” is
equal to 500 . NaN (Not a Number) is not equal to anything, including NaN . Positive and
negative zeros are equal. Two objects are equal if they refer to the same object. Two Bool-
ean operands are equal if they are both true or both false . Null and undefined types are
equal. To test any of the expressions shown in Table 5.7, use the JavaScript Console. Fig-
ure 5.8 shows an example using Firefox.
Table 5.7 Equality Test with Strings and Numbers
Test
Are They Equal?
"William" == "William"
true
"william" == "William"
false
5 == 5.0
true
"54" == 54
true
"5.4" == 5.4
true
NaN == NaN
false
null == null
true
-0 == +0
true

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