Computer Science
Mathematics
Logic
JAVASCRIPT VARIABLE DECLARATION CHECK
There are times when we need to call javascript functions that exist on different files that may not be loaded yet. In such cases we'll need to check if that variable is defined.
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if (
typeof
(var1) ===
"undefined"
) {
// write code here...
}
1
Firefox
v38.0.5 as of 6/21/2015
2
Internet Explorer v11
3
Chrome
v41 as of 4/11/2015
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Safari