Difference Betwixt Substr Vs Substring Method Inwards Javascript - Tutorial Example

JavaScript provides 2 similar looking String manipulation function, substr too substring, though both are used to instruct substring from an String, at that spot is a subtle difference betwixt substring too substr method inwards JavaScript. If you lot aspect at at that spot signature, both substr(to, length) too substring(to, from) both takes 2 parameters, but substr takes length of substring to live returned, field substring takes terminate index (excluding) for substring.This top dog divergence volition live to a greater extent than clear when nosotros volition run into couplet of examples of using substr too substring inwards JavaScript code. By the way this is likewise a practiced JavaScript enquiry too ofttimes asked to spider web developers during HTML, CSS too JavaScript interviews, along amongst how to foreclose multiple submission of shape data. Because of extensive uses of String, this cognition is non solely of import from interview quest of persuasion but likewise from evolution quest of view. It likewise helps to trim down subtle bugs inwards JavaScript code, which is innovate because of wrong usage of substr or substring method.

Difference betwixt SubString too SubStr method inwards JavaScript

As I said inwards starting fourth dimension paragraph, top dog divergence betwixt substring too substr JavaScript method are inwards at that spot minute parameter, substring own got index of lastly graphic symbol + 1, field substr() method gets expected length of substring. Let's  convey a aspect at next examples :

var str = "JavaScript";

alert(str.substring(0, 4));  // would impress "Java"

Since JavaScript index are nix based, In inwards a higher house instance starting index is nix (including), which is starting fourth dimension graphic symbol too terminate index is 4 (excluding), too therefore substring would live "Java". On the other hand, if nosotros apply similar declaration to substr method, nosotros volition instruct same result, but on unlike way.

var str = "JavaScript"

alert(str.substr(0, 4));  // this volition likewise render "Java"

Though this code likewise returns Java, but hither logic is different, every bit hither starting index is nix too length of substring is 4, which agency 4 characters long string, which starts from starting fourth dimension character, that's why "Java". If nosotros apply unlike declaration nosotros volition instruct unlike effect e.g.

var str = "JavaScript"

alert(str.substr(4, 6)); // this volition render Script

alert(str.substring(4, 6)); // this volition render "Sc"

Here, you lot tin clearly run into that both substr and substring are returning unlike result, because starting index is non zero. Because of this many spider web developer often confuse too they think that substr and substring comport identically, which is non true. You should live really careful, field using substr() and substring(), otherwise it volition do difficult to discovery subtle bugs. There is roughly other method called slice() which tin likewise live used for creating smaller substring from String inwards JavaScript, too you lot tin think of it to avoid whatsoever confusion betwixt substring too substr in JavaScript.

That's all nearly difference betwixt substr too substring method inwards JavaScript, only yell upward that divergence is inwards the minute argument. The minute declaration of substring method takes terminate index, which is excluded from end substring, field minute declaration of substr method takes maximum length of expected substring.

Further Learning
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