In JavaScript we have a function isNan (Not a number) to check whether the value is a number or not. It takes only one parameter, value and returns true or false, we will check here some values and conditions to understand it better.
It supports in all browsers.
isNaN(123); // false -- 123 is a number
isNaN(1.23); // false -- 1.23 is a number
isNaN(12 - 3); // false -- 12-3 = 9 is a number
isNaN(0); // false -- 0 is a number
isNaN('3S'); // true -- 3S is not a number but string so not a number
isNaN('abcd'); // true -- abcd is a string so not a number
isNaN('01/02/20013'); // true -- 01/02/20013 is a date so not a number
isNaN('01:02:03'); // true -- 01:02:03 is time so not a number
var a; var b; // value not defined
isNaN(a/b); // true
a=10;
isNaN(a/b); // true -- because b is not defined
b=5;
isNaN(a/b); // false -- a/b=10/5 = 2 is a number
var a= [1, 2, 3,4,5,];
var b; // not initialized
for(i=0; i<a.length; i++)
b = b + a[i]
isNaN(b); // true -- because b is undefined.
b was not initialize before the loop start, so b is undefined so undefined + any value = undefined
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| By Jason Olivera On 30 Mar, 13 Viewed: 535 |
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