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comparison core-javascript/equality.rst @ 204:45e7d5e8fa97

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Use double backticks for inline code
author Radomir Dopieralski <radomir.dopieralski@allegro.pl>
date Wed, 16 May 2012 16:53:27 +0200
parents 6ea48585f70c
children a808230bc5dd
comparison
equal deleted inserted replaced
203:92c876338c31 204:45e7d5e8fa97
149 .. code-block:: javascript 149 .. code-block:: javascript
150 150
151 js> +a === +b 151 js> +a === +b
152 true 152 true
153 153
154 When the value cannot be converted to a number, you will get a `NaN` value. 154 When the value cannot be converted to a number, you will get a ``NaN`` value.
155 `NaN` is never equal to anything, even to itself. 155 `NaN` is never equal to anything, even to itself.
156 156
157 Alternatively, you can use the `parseInt` and `parseFloat` functions to convert 157 Alternatively, you can use the ``parseInt`` and ``parseFloat`` functions to convert
158 strings to number -- their behavior is slightly different, as they will silently 158 strings to number -- their behavior is slightly different, as they will silently
159 ignore all non-number characters in the string. 159 ignore all non-number characters in the string.
160 160
161 .. code-block:: javascript 161 .. code-block:: javascript
162 162
163 js> parseInt('3abc1') 163 js> parseInt('3abc1')
164 3 164 3
165 js> +'3abc1' 165 js> +'3abc1'
166 NaN 166 NaN
167 167
168 Because `NaN` is never equal to anything, even itself, you cannot check whether 168 Because ``NaN`` is never equal to anything, even itself, you cannot check whether
169 you got `NaN` as a result with `==` or `===`. You have to use the `isNaN` function 169 you got ``NaN`` as a result with ``==`` or ``===``. You have to use the ``isNaN``
170 for that. 170 function for that.
171 171
172 Compare as boolean 172 Compare as boolean
173 ------------------ 173 ------------------
174 174
175 To convert an expression to a boolean value, it's most convenient to use the 175 To convert an expression to a boolean value, it's most convenient to use the
176 `!` boolean negation operator twice, like this: 176 ``!`` boolean negation operator twice, like this:
177 177
178 .. code-block:: javascript 178 .. code-block:: javascript
179 179
180 js> !!0 === !!'' 180 js> !!0 === !!''
181 true 181 true