How to Effectively Check for Empty, Undefined, or Null Strings in JavaScript?

Checking for Empty, Undefined, or Null Strings in JavaScript

JavaScript does not have a dedicated string.Empty value. Instead, checking for empty strings requires conditionals based on truthy or falsy values, or strict equality against the empty string.

Checking for Truthy or Falsy Values

To check if a string is not empty, consider the truthy condition:

if (strValue) {
    // strValue is non-empty string, true, 42, Infinity, [], ...
}

Conversely, to check if a string is empty, consider the falsy condition:

if (!strValue) {
    // strValue is empty string, false, 0, null, undefined, ...
}

Checking for Empty Strings Strictly

For strict checks against empty strings, use the === operator:

if (strValue === "") {
    // strValue is an empty string
}

To check if a string is not strictly empty, use the !== operator:

if (strValue !== "") {
    // strValue is not an empty string
}

Remember that empty strings are equivalent to undefined and null in truthy/falsy checks, but they are distinct when checking for strict equality.

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