JavaScript isNull: Checking for Null Values

isnull javascript To check for null SPECIFICALLY you would use this: if (result === null). also you can cehck variable are Null, Empty String, Undefined, False, Zero and NaN Test.

isnull javascript – How to Check for null in JavaScript?

if(!pass || !cpass || !email || !cemail || !user){

return results == null ? 0 : (results[1] || 0);

Null Test:

if (result === null)

- result = ""; (false) typeof result = string

- result = null; (true) typeof result = object

- result = undefined; (false) typeof result = undefined

- result = false; (false) typeof result = boolean

- result = 0; (false) typeof result = number

- result = NaN; (false) typeof result = number

Empty String Test:

if (result === '')

- result = ''; (true) typeof result = string

- result = null; (false) typeof result = object

- result = undefined; (false) typeof result = undefined

- result = false; (false) typeof result = boolean

- result = 0; (false) typeof result = number

- result = NaN; (false) typeof result = number

Undefined Test:

if (typeof result == "undefined")

-- or --

if (result === undefined)

- result = ''; (false) typeof result = string

- result = null; (false) typeof result = object

- result = undefined; (true) typeof result = undefined

- result = false; (false) typeof result = boolean

- result = 0; (false) typeof result = number

- result = NaN; (false) typeof result = number

Don’t Miss : Check If Object Is Empty In VueJS

False Test:

if (result === false)

- result = ''; (false) typeof result = string

- result = null; (false) typeof result = object

- result = undefined; (false) typeof result = undefined

- result = false; (true) typeof result = boolean

- result = 0; (false) typeof result = number

- result = NaN; (false) typeof result = number

Zero Test:

if (result === 0)

- result = ''; (false) typeof result = string

- result = null; (false) typeof result = object

- result = undefined; (false) typeof result = undefined

- result = false; (false) typeof result = boolean

- result = 0; (true) typeof result = number

- result = NaN; (false) typeof result = number

NaN Test:

if (typeof result == 'number' && !parseFloat(result) && result !== 0)

-- or --

if (isNaN(result))

- result = ''; (false) typeof result = string

- result = null; (false) typeof result = object

- result = undefined; (false) typeof result = undefined

- result = false; (false) typeof result = boolean

- result = 0; (false) typeof result = number

- result = NaN; (true) typeof result = number

I hope you get an idea about isnull javascript.

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