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how to check a var whether is number in js

js check var is number

Number.isInteger(NaN)
false
Number.isInteger(``)
false
Number.isInteger(0)
true
Number.isInteger(null)
false
Number.isInteger(undefined)
false

typeof === "number"

typeof NaN;
// "number"

typeof undefined;
// "undefined"
typeof ``;

// "string"
typeof null;
// "object"

let x = NaN;
// NaN

isNaN(x);
// true

isNaN(0);
// false

isNaN(``);
// false

isNaN(null);
// false

isNaN(undefined);
// true

https://mkyong.com/javascript/check-if-variable-is-a-number-in-javascript/

https://dev.to/skptricks/check-if-variable-is-a-number-in-javascript-1f10

https://www.skptricks.com/2018/11/check-if-variable-is-number-in-js.html

https://medium.com/javascript-in-plain-english/how-to-check-for-a-number-in-javascript-8d9024708153

https://www.w3schools.com/jsref/jsref_isnan.asp

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TS

https://www.typescriptlang.org/docs/handbook/type-checking-javascript-files.html

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