| 1 |
One must NEVER access an undefined variable
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if in JavaScript that is linked to LiveConnect, one gets a Java error which requires restarting Netscape .....
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If in less sensitive JavaScript, execution of script stops and action unpredictable
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| 2 |
Until page fully formed, any of its properties can be undefined
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| 3 |
Modern JavaScript allows one to test if variables are defined and so avoid these errors
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| 4 |
in a.b.c.d.e type reference, one must first test if a exists, then b, then ....
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| 5 |
WWutility.js includes
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WW_isdefined(property) returns true if argument is defined as a property or method
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WW_isitawindow(possibleframe) returns true if argument is a window or frame
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