Javascript string and character comparision [duplicate]

Question

Why does 'Mystery!' <= 'Z' equal true but 'the' <= 'Z' equal false but both 'Mystery!' >= 'A' and 'the' >= 'A' equal true. How does such comparision work?

Because 'B' < 'a'. Characters are usually (on most systems) in this order: ..., A, B, ..., Z, ... , a, b, c, ... — ibrahim mahrir
– ibrahim mahrir, Commented Apr 21, 2017 at 19:47
it depends on characters' codes. In fact what gets compared are the codes of the symbols. — curveball
– curveball, Commented Apr 21, 2017 at 19:47
@kindUser Just closing it without even reading the duplicate candidate. How typical. — ibrahim mahrir
– ibrahim mahrir, Commented Apr 21, 2017 at 19:55
@ibrahimmahrir The "on most systems" part is misleading. JavaScript always uses the UTF-16 encoding of the Unicode character set for strings. What might vary by source, user and time is the locale but the binary comparison operators always use the UTF-16 lexicographic ordering. — Tom Blodget
– Tom Blodget, Commented Apr 22, 2017 at 20:20

parallaxis · Accepted Answer · 2017-04-21 19:49:27Z

3

it's comparing the UTF-16 code for the string value. Try the same comparisons with charCodeAt method to understand what's happening here

'y'.charCodeAt() <= 'Z'.charCodeAt()

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/charCodeAt

answered Apr 21, 2017 at 19:49

parallaxis

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Comments

Zac · Accepted Answer · 2017-04-22 21:59:16Z

2

Upper case letters before lower case letters.

M = ascii value 77
Z = 90

77 < 90

t = 116
Z = 90

116 !< 90

See more here: www.asciitable.com

edited Apr 22, 2017 at 21:59

answered Apr 21, 2017 at 19:50

Zac

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1 Comment

Tom Blodget Over a year ago

JavaScript doesn't use ASCII for built-in text datatypes. I'm not aware of any language that does.

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