Regular Expressions 101

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An explanation of your regex will be automatically generated as you type.
Detailed match information will be displayed here automatically.
  • All Tokens
  • Common Tokens
  • General Tokens
  • Anchors
  • Meta Sequences
  • Quantifiers
  • Group Constructs
  • Character Classes
  • Flags/Modifiers
  • Substitution
  • A single character of: a, b or c
    [abc]
  • A character except: a, b or c
    [^abc]
  • A character in the range: a-z
    [a-z]
  • A character not in the range: a-z
    [^a-z]
  • A character in the range: a-z or A-Z
    [a-zA-Z]
  • Any single character
    .
  • Alternate - match either a or b
    a|b
  • Any whitespace character
    \s
  • Any non-whitespace character
    \S
  • Any digit
    \d
  • Any non-digit
    \D
  • Any word character
    \w
  • Any non-word character
    \W
  • Non-capturing group
    (?:...)
  • Capturing group
    (...)
  • Zero or one of a
    a?
  • Zero or more of a
    a*
  • One or more of a
    a+
  • Exactly 3 of a
    a{3}
  • 3 or more of a
    a{3,}
  • Between 3 and 6 of a
    a{3,6}
  • Start of string
    ^
  • End of string
    $
  • A word boundary
    \b
  • Non-word boundary
    \B

Regular Expression
No Match

/
/
gm

Test String

Code Generator

Language

Generated Code

const regex = /(?i)^\s*(.*((p|post)[-.\s]*(o|off|office)[-.\s]*(b|box|bin)[-.\s]*)|.*((p|post)[-.\s]*(o|off|office)[-.\s]*)|.*((p|post)[-.\s]*(b|box|bin)[-.\s]*)|(box|bin)[-.\s]*)(#|n|num|number)?\s*\d+/gm; // Alternative syntax using RegExp constructor // const regex = new RegExp('(?i)^\\s*(.*((p|post)[-.\\s]*(o|off|office)[-.\\s]*(b|box|bin)[-.\\s]*)|.*((p|post)[-.\\s]*(o|off|office)[-.\\s]*)|.*((p|post)[-.\\s]*(b|box|bin)[-.\\s]*)|(box|bin)[-.\\s]*)(#|n|num|number)?\\s*\\d+', 'gm') const str = `-- Match post office box 1 post office bin 1 post office b 1 post off box 1 post off bin 1 post off b 1 post o box 1 post o bin 1 post o b 1 p office box 1 p office bin 1 p office b 1 p off box 1 p off bin 1 p off b 1 p o box 1 p o bin 1 p o b 1 p-o-b-1 p.o.b.1 POB1 pob1 pob#1 pob #1 pob # 1 p o b # 1 x p o b # 1 x pob n1 pob num1 pob number1 foo pob1 1 pob1 box 1 bin 1 box-1 box.1 box1 BOX1 box#1 box #1 box # 1 box # 1 x box # 1 x po 1 po n1 PO 1 pb 1 pb n1 PB 1 -- No Match foo box 1 b1 #1 1 box 1 1 pob post 1 n1 number1 num1 post office box post office bin post office b post off box post off bin post off b post o box post o bin post o b p office box p office bin p office b p off box p off bin p off b p o box p o bin p o b p-o-b- p.o.b. POB pob pob# pob # pob # p o b # x p o b # x pob n pob num pob number foo pob box bin box- box. box BOX box# box # box # box # x box # x po po n PO pb pb n PB`; // Reset `lastIndex` if this regex is defined globally // regex.lastIndex = 0; let m; while ((m = regex.exec(str)) !== null) { // This is necessary to avoid infinite loops with zero-width matches if (m.index === regex.lastIndex) { regex.lastIndex++; } // The result can be accessed through the `m`-variable. m.forEach((match, groupIndex) => { console.log(`Found match, group ${groupIndex}: ${match}`); }); }

Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for JavaScript, please visit: https://developer.mozilla.org/en/docs/Web/JavaScript/Guide/Regular_Expressions