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=== examples === | === examples === | ||
things to watch out for in automatic type conversion. | |||
<syntaxhighlight lang="javascript"> | |||
"Apollo" + 5; // Apollo5 | |||
null + "ify": // nullify | |||
"5" * 5; // 25 | |||
"strawberry" * 5; // NaN | |||
NaN == NaN; // false use isNaN() function instead | |||
</syntaxhighlight> | |||
<syntaxhighlight lang="javascript"> | |||
</syntaxhighlight> | |||
automatic type conversion. To disallow automatic type conversion, use === or !== operators. | |||
<syntaxhighlight lang="javascript"> | |||
false == 0; // true | |||
"" == 0; // true | |||
"5" == 5; // true | |||
</syntaxhighlight> | |||
Check if something is null or defined. if a variable has been defined ("var something") but it hasn't been assigned anything, it returns undefined. All of functions that have no return values also return undefined. | |||
<syntaxhighlight lang="javascript"> | |||
if (something == undefined) // either undefined or null | |||
</syntaxhighlight> | |||
<syntaxhighlight lang="javascript"> | <syntaxhighlight lang="javascript"> | ||