When Comparing Strings in JavaScript, What Lexicographical Ordering is Used?

Understanding String Comparison in JavaScript

The JavaScript comparison operator (<) is used to compare two values. When comparing strings, JavaScript uses lexicographical ordering, which means it compares the characters of the strings individually until it finds a difference or reaches the end of one of the strings.

Consider the example:

<code class="javascript">if ('11' < '3') alert('true');</code>

This comparison evaluates to true because:

• The first character of '11' is '1', which has a Unicode code point of 49.
• The first character of '3' is '3', which has a Unicode code point of 51.
• 49 is less than 51 lexicographically, hence '11' is considered less than '3'.

Lexicographical Ordering

Lexicographical ordering is based on the Unicode code points of the characters. Characters are compared in order from left to right. For example:

• "abc" < "abd" because 'c' has a lower Unicode code point than 'd'.
• "31" < "32" because '1' has a lower Unicode code point than '2'.

Implicit Type Conversion

In the example above, the strings '11' and '3' are implicitly converted to numbers before comparison, and the numeric comparison is performed. However, if you explicitly convert the strings to numbers using the ' ' operator, the comparison will be different:

<code class="javascript">if (+'11' < '3') alert('true'); // evaluates to false</code>

Conclusion

String comparison in JavaScript follows lexicographical ordering, with strings being compared character by character. Understanding this behavior is crucial when working with string-based comparisons in JavaScript code.

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