Is There a Universal JavaScript Function to Check for Null, Undefined, or Blank Variables?

Is there a universal JavaScript function to check for null, undefined, or blank variables?

The provided code checks for undefined, null, and zero-length values. However, there is an alternative approach that is more comprehensive and covers a wider range of falsy values.

Solution using Truthy Values:

To check if a variable has a truthy value, you can simply use the following statement:

if (value) {
    // do something..
}

This will evaluate to true if the value is not one of the following falsy values:

• null
• undefined
• NaN
• empty string ("")
• 0
• false

Solution using typeof Operator:

If you need to check if a variable exists (i.e., is declared), you can use the typeof operator:

if (typeof foo !== 'undefined') {
    // foo could get resolved and it's defined
}

This checks if the variable foo is not undefined, indicating that it exists.

Note: If you are certain that a variable is declared, you can directly check for its truthy value using the first solution.

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