Menu
What is the difference between
alert("abc".substr(0,2)); and
alert("abc".substring(0,2)); They both seem to output “ab”.
633
substring is the sql operation defined in the sql standard ISE:IEC 9075:1992. substr is an old syntax used by oracle. This wrong syntax is completely inconsistent with sql usage of real english words, never abbreviations. Oracle still does not support the standard syntax.
slice() extracts parts of a string and returns the extracted parts in a new string. substr() extracts parts of a string, beginning at the character at the specified position, and returns the specified number of characters. substring() extracts parts of a string and returns the extracted parts in a new string.
a substring is a subsequence of a string in which the characters must be drawn from contiguous positions in the string. For example the string CATCGA, the subsequence ATCG is a substring but the subsequence CTCA is not.
A big difference with substring() is that if the 1st argument is greater than the 2nd argument, substring() will swap them. slice() returns an empty string if the 1st argument is greater than the 2nd argument.
The difference is in the second argument. The second argument to substring is the index to stop at (but not include), but the second argument to substr is the maximum length to return.
Links?
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/substr
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/substring
185
substr (MDN) takes parameters as (from, length).substring (MDN) takes parameters as (from, to).
Update: MDN considers substr legacy.
alert("abc".substr(1,2)); // returns "bc" alert("abc".substring(1,2)); // returns "b" You can remember substring (with an i) takes indices, as does yet another string extraction method, slice (with an i).
When starting from 0 you can use either method.
21
If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
Donate Us With
