each are used to get a substring from a String, there’s a delicate distinction
between substring and substr technique in JavaScript. For those who have a look at their signature, each substr(to,
size) and substring(to, from) each take two parameters, however substr takes the size of the substring to be returned, whereas substring takes finish index (excluding)
for substring. This predominant distinction shall be extra clear once we will see a few examples of utilizing substr and substring in JavaScript code.
By the best way, that is additionally a preferred JavaScript query and continuously requested internet builders throughout HTML, CSS, and JavaScript interviews, together with find out how to forestall a number of submissions of type knowledge, and distinction between == vs === and distinction between var, let, and const key phrase in JavaScript. I’ve mentioned them earlier than, if you have not learn them you can even test them.
Due to the intensive makes use of of String, this information isn’t solely necessary from the interview perspective but in addition from a growth perspective. It additionally helps to scale back delicate bugs in JavaScript code, which is launched due to incorrect use of substr or substring technique.
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Distinction between SubString and SubStr technique in JavaScript
As I mentioned within the first paragraph, the primary distinction between substring and substr JavaScript technique is in there the second parameter, substring settle for index of final character + 1, whereas substr() technique will get anticipated size of the substring. Let’s check out following
examples :
var str = “JavaScript”;
alert(str.substring(0, 4)); // would print
“Java”
Since JavaScript indexes are zero-based, Within the above instance beginning index is
zero (together with), which is the primary character, and the tip index is 4 (excluding), so
substring can be “Java”. Alternatively, if we
apply the same argument to substr technique, we are going to get the identical consequence, however on
completely different means.
var str = “JavaScript”
alert(str.substr(0, 4)); // this will even
return “Java”
Although this code additionally returns Java, right here logic is completely different, as right here
beginning index is zero and the size of the substring is 4, which suggests 4
characters lengthy string, which begins from the primary character, that is why “Java”. If we
apply completely different arguments we are going to get completely different outcomes e.g.
var str = “JavaScript”
alert(str.substr(4, 6));
// this can return Script
alert(str.substring(4, 6));
// this can return “Sc”
Right here, you possibly can clearly see that each substr and substring arereturning completely different outcomes as a result of the beginning index isn’t zero. Due to this
many internet builders typically confuse and assume that substr and substring
behave identically, which isn’t true.
You have to be very cautious whereas utilizing
substr() and substring(), in any other case it should create arduous to search out delicate bugs. There
is one other technique known as slice() which may also be used for
creating smaller substring from String in JavaScript, and you may consider it
to keep away from any confusion between substring and substr in JavaScript.
That is all in regards to the distinction between substr and substring strategies in
JavaScript, simply remembers that the distinction is within the second argument. The second argument of the substring technique takes the tip index, which is excluded from the ultimate substring, whereas the second argument of substr technique takes the utmost size of the anticipated substring.
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