Case insensitive string comparison in javascript

Question

Can someone explain why this is the case?

console.log('AB_CD' > 'AB_C_D'); //false
console.log('ab_cd' > 'ab_c_d'); //true

"A".charCodeAt(0) -> 65; "a".charCodeAt(0) -> 97; "_".charCodeAt(0) -> 95 — VLAZ
– VLAZ, Commented Mar 1, 2021 at 9:13
Because _ is larger than any upper-case letter but smaller than any lower-case letter, i.e. 'D' < '_' (first line) but 'd' > '_' (second line) — CherryDT
– CherryDT, Commented Mar 1, 2021 at 9:14

greenBox · Accepted Answer · 2021-03-01 09:29:49Z

2

Strings are compared using character codes, which you can learn more about reading this tutorial

In this first comparison ('AB_CD' > 'AB_C_D'), the character code for D and _ are 68 and 95, respectively, which explains why the expression evaluates as false.

A: 65; A: 65
B: 66; B: 66
_: 95; _: 95
C: 67; C: 67
D: 68; _: 95

In the second comparison ('ab_cd' > 'ab_c_d'), the character code for d and _ are 100 and 95, respectively, which explains why the expression evaluates as true.

a: 97;  a: 97
b: 98;  b: 98
_: 95;  _: 95
c: 99;  c: 99
d: 100; _: 95

edited Mar 1, 2021 at 9:29

answered Mar 1, 2021 at 9:23

greenBox

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