JavaScript syntax
part 14/31 · 107.4 KB total
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Regular expression
/expression/.test(string); // returns Boolean
"string".search(/expression/); // returns position Number
"string".replace(/expression/, replacement);
// Here are some examples
if (/Tom/.test("My name is Tom")) console.log("Hello Tom!");
console.log("My name is Tom".search(/Tom/)); // == 11 (letters before Tom)
console.log("My name is Tom".replace(/Tom/, "John")); // == "My name is John"
Character classes
// \d - digit
// \D - non digit
// \s - space
// \S - non space
// \w - word char
// \W - non word
// [ ] - one of
// [^] - one not of
// - - range
if (/\d/.test('0')) console.log('Digit');
if (/[0-9]/.test('6')) console.log('Digit');
if (/[13579]/.test('1')) console.log('Odd number');
if (/\S\S\s\S\S\S\S/.test('My name')) console.log('Format OK');
if (/\w\w\w/.test('Tom')) console.log('Hello Tom');
if (/[a-zA-Z]/.test('B')) console.log('Letter');
Character matching
// A...Z a...z 0...9 - alphanumeric
// \u0000...\uFFFF - Unicode hexadecimal
// \x00...\xFF - ASCII hexadecimal
// \t - tab
// \n - new line
// \r - CR
// . - any character
// | - OR
if (/T.m/.test('Tom')) console.log ('Hi Tom, Tam or Tim');
if (/A|B/.test("A")) console.log ('A or B');
Repeaters
// ? - 0 or 1 match
// * - 0 or more
// + - 1 or more
// {n} - exactly n
// {n,} - n or more
// {0,n} - n or less
// {n,m} - range n to m
if (/ab?c/.test("ac")) console.log("OK"); // match: "ac", "abc"
if (/ab*c/.test("ac")) console.log("OK"); // match: "ac", "abc", "abbc", "abbbc" etc.
if (/ab+c/.test("abc")) console.log("OK"); // match: "abc", "abbc", "abbbc" etc.
if (/ab{3}c/.test("abbbc")) console.log("OK"); // match: "abbbc"
if (/ab{3,}c/.test("abbbc")) console.log("OK"); // match: "abbbc", "abbbbc", "abbbbbc" etc.
if (/ab{1,3}c/.test("abc")) console.log("OK"); // match: "abc", "abbc", "abbbc"
Anchors
// ^ - string starts with
// $ - string ends with
if (/^My/.test("My name is Tom")) console.log ("Hi!");
if (/Tom$/.test("My name is Tom")) console.log ("Hi Tom!");
Subexpression
// ( ) - groups characters
if (/water(mark)?/.test("watermark")) console.log("Here is water!"); // match: "water", "watermark",
if (/(Tom)|(John)/.test("John")) console.log("Hi Tom or John!");
Flags
// /g - global
// /i - ignore upper/lower case
// /m - allow matches to span multiple lines
console.log("hi tom!".replace(/Tom/i, "John")); // == "hi John!"
console.log("ratatam".replace(/ta/, "tu")); // == "ratutam"
console.log("ratatam".replace(/ta/g, "tu")); // == "ratutum"
Advanced methods
my_array = my_string.split(my_delimiter);
// example
my_array = "dog,cat,cow".split(","); // my_array==["dog","cat","cow"];
my_array = my_string.match(my_expression);
// example
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