#JAVASCRIPT REGEX REPLACE CODE#

Ranges, delimited by square brackets, match a range of characters: ExpressionДЇind any character NOT between the bracketsДЇind any character between the brackets (any digit)ДЇind any character NOT between the brackets (any non-digit) Modifiers change the default matching behavior (return the first match, use case-sensitive matching, and match only the first line of a multi-line variable): Modifier The behavior of the regular expression matching engine is changed and extended through the use of modifiers, character ranges, class type meta-characters, and quantifiers. Search by a regex, insensitively, globally (all occurrences): console.log( 'my cat, Cat'.replace(/Cat/ig, 'Dog') ) // -> my Dog, Dog Search by a regex, insensitively, for the first occurrence: console.log( 'my cat, Cat'.replace(/Cat/i, 'Dog') ) // -> my Dog, Cat Search by a quoted literal for the first occurrence: console.log( 'my cat, Cat'.replace('Cat', 'Dog') ) // -> my cat, Dog Compare the results of the following three calls: The Javascript replace() function takes a regex and returns a string, possibly modified by the pattern if the search is successful. Read on for mention of the RegExp() function, which makes this kind of typo less common. It is a frequent source of debugging rage to think one is searching with the power of regex matching only to discover a quoted string. NOTE: Javascript /Cat/ is a very different beast than is 'Cat' in this context: the former is a regex, the latter a string. Let string = 'my cat, Cat' // search in this stringД¬onsole.log( arch( regex ) ) // -> 3Д®quivalent to the above, search() may be invoked directly on any string variable: console.log( 'my cat, Cat'.search(/Cat/) ) // -> 10Д¬onsole.log( 'my cat, Cat'.search(/Cat/i) ) // -> 3

let regex = /Cat/i // case-insensitive search for 'Cat' For example, here we search through string for 'Cat' with the imodifier (ignore case during the search). The Javascript search() function takes a regex and returns the position within the string where the match is found (or a -1 if not found). The Javascript replace() function takes a regular expression and returns a modified string where the pattern is replaced. The Javascript search() function takes a regular expression to search for a match, and returns the position of the match.

the forward-slashes / are the pattern delimiters.

/cat/i is a complete regular expression.

Using the string /cat/i as an example, regex terminology is: Javascript Regular Expression Basics SyntaxДЄ regex has the syntax /pattern/modifiers. Some people, when confronted with a problem, think вЂњI know, IвЂ™ll use regular expressions.вЂќ Now they have two problems. Regex are not intuitive and seemingly always require some tweaking to get right, so an online regex tester is essential. *cat* finds the words containing the root 'cat' in 'A cat, not a dog, and the toys the catвЂ™s scattered about - categorically a catastrophe!' Regex find use across a wide variety of complex use cases, some examples:Д¬olou?r finds the similarly-spelled words color (American) and colour (Commonwealth)

#JAVASCRIPT REGEX REPLACE CODE#

Regular expressions have many uses in any code which works with text strings (or streaming textual data). This blog entry will cover these search patterns and various ways to use regex within Javascript.

Regex (or regexp) are flexible, powerful, and make writing understandable and maintainable programs much easier. Regular expressions provide the ability to 'find' and 'find and replace' data through text strings which specify search patterns.

Javascript regex replace