What the algorithm work behind string comparison in javascript, for example
'bc' > 'ac' = true/false ?
'ac' > 'bc' = true/false ?
4 Answers
This is calculated using The Abstract Relational Comparison Algorithm in ECMA-5. The relevant part is quoted below.
4. Else, both px and py are Strings
a) If py is a prefix of px, return false. (A String value p is a prefix
of String value q if q can be the result of concatenating p and some
other String r. Note that any String is a prefix of itself, because
r may be the empty String.)
b) If px is a prefix of py, return true.
c) Let k be the smallest nonnegative integer such that the character
at position k within px is different from the character at position
k within py. (There must be such a k, for neither String is a prefix
of the other.)
d) Let m be the integer that is the code unit value for the character
at position k within px.
e) Let n be the integer that is the code unit value for the character
at position k within py.
f) If m < n, return true. Otherwise, return false.
Comments
Strings are compared character by character, so the very first letter is the most significant, hence
'bc' > 'ac' = true/false ? => true
'ac' > 'bc' = true/false ? => false
if the first letter will be equal then, second will be compared and so on, till one of them will be greater or less or equal.
Comments
Not only in javascript , In simple, all string comparison algorithm will follow the lexicographical order or dictionary order, which means it will check each character by character, if some mismatches, you can decide the result
True:
ant < any
aaa < aab
aab < b
b < baa
Comments
JavaScript compares strings by the order of Unicode codepoints and lexicographically compares UTF-16 code units.
From your question:
'bc' > 'ac' // Because 'b' comes after 'a'.
Comments
bis greater thanaetc.