Difference Betwixt Substr Vs Substring Method Inwards Javascript - Tutorial Example

JavaScript provides 2 like looking String manipulation function, substr too substring, though both are used to larn substring from an String, in that place is a subtle difference betwixt substring too substr method inwards JavaScript. If y'all aspect at in that place signature, both substr(to, length) too substring(to, from) both takes 2 parameters, but substr takes length of substring to live on returned, spell substring takes halt index (excluding) for substring.This primary departure volition live on to a greater extent than clear when nosotros volition encounter duo of examples of using substr too substring inwards JavaScript code. By the way this is equally good a adept JavaScript interrogation too ofttimes asked to spider web developers during HTML, CSS too JavaScript interviews, along amongst how to forestall multiple submission of cast data. Because of extensive uses of String, this noesis is non solely of import from interview signal of persuasion but equally good from evolution signal of view. It equally good helps to cut down subtle bugs inwards JavaScript code, which is innovate because of wrong utilisation of substr or substring method.

Difference betwixt SubString too SubStr method inwards JavaScript

As I said inwards showtime paragraph, primary departure betwixt substring too substr JavaScript method are inwards in that place minute parameter, substring convey index of finally grapheme + 1, spell 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 higher upwards instance starting index is nix (including), which is showtime grapheme too halt index is 4 (excluding), too then substring would live on "Java". On the other hand, if nosotros apply like declaration to substr method, nosotros volition larn same result, but on dissimilar way.

var str = "JavaScript"

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

Though this code equally good returns Java, but hither logic is different, equally hither starting index is nix too length of substring is 4, which way 4 characters long string, which starts from showtime character, that's why "Java". If nosotros apply dissimilar declaration nosotros volition larn dissimilar number e.g.

var str = "JavaScript"

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

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

Here, y'all tin clearly encounter that both substr and substring are returning dissimilar result, because starting index is non zero. Because of this many spider web developer often confuse too they think that substr and substring acquit identically, which is non true. You should live on really careful, spell using substr() and substring(), otherwise it volition exercise difficult to honour subtle bugs. There is around other method called slice() which tin equally good live on used for creating smaller substring from String inwards JavaScript, too y'all tin think of it to avoid whatsoever confusion betwixt substring too substr in JavaScript.

That's all most difference betwixt substr too substring method inwards JavaScript, only recollect that departure is inwards the minute argument. The minute declaration of substring method takes halt index, which is excluded from finally substring, spell minute declaration of substr method takes maximum length of expected substring.

Further Learning
JavaScript Fundamentals past times Liam McLennan
ES6 Javascript: The Complete Developer's Guide
JavaScript: Understanding the Weird Parts

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