Regular expression in javascript

Regular expression in javascript

example of the use, if you want to extract "my name" from this string '"name":"my name"'

var ret = '"name":"my name"';

var rets = ret.match(/name[\\'"+]:[\\'"+]([^\0'"]+)/i)||[,];

you will get rets[0] = "name":"my name" 

and you will get rets[1] = "my name"

explanation:

.match is the method of string type. this is actual structure .match(//i)

i -> indicate that we don't care the case

so if you have string = '"Name":"my name"' or '"nAme":"my name"' it will also work

now look at this regular expression

name >> begin of search

• we want to find the text that has "name" at the begin of the search
• your name : >> this will work
• your nnme : >> this will not work

[\\"'+] >> represent next characters after above word

• next character must be \  " or ', at least 1
• your name" : >> this will work
• your name: >> this will not work 
• it can be more than 1
• your name"' :>> this will work
• your name\" :>> this will work

: >> represent next character after above pattern

• your name": >> this will work
• your name""x >> this will not work

[\\"'+] >> represent next characters after above word

• next character must be \  " or ', at least 1
• your name":" >> this will work
• your name: " >> this will not work 
• it can be more than 1
• your name"':" :>> this will work
• your name\":\" :>> this will work

([^\0'"]+) >> represent group of text that after above word

• it can be any character but not ascii 0 and not " and not '
• your name":"sss" :>> this will work
• your name":"sss :>> this will not work
• 
  
• it can be more than 1
• your name":"s" :>> this will work
• your name":"sss" :>> this will work

let's look at the function method

ret.match(/name[\\'"+]:[\\'"+]([^\0'"]+)/i) 

>> this will return array if match

>> and return null if not match

ret.match(/name[\\'"+]:[\\'"+]([^\0'"]+)/i) || [,]

>> always return array, if match will return matching array

>> if not match you will get empty array of 2 index