[Javascript] How to use JavaScript's String.replace

console.clear()

simpleStringReplace()
simpleRegexReplace()
globalRegexReplace()
regexReplaceGroup()
advancedRegexReplaceGroup()
simpleFunctionReplacer()
regexFunctionReplacerGroup()

console.log(‘Tests passed‘)


function simpleStringReplace() {
  var input = ‘Perl is the best programming language‘
  var expected = ‘JavaScript is the best programming language‘
  
  var result = input.replace(‘Perl‘, ‘JavaScript‘)
  expect(result).toEqual(expected)
}

function simpleRegexReplace() {
  var input = ‘My phone number is 123-555-3344‘
  var expected = ‘My phone number is xxx-xxx-xxxx‘
  
  var result = input.replace(/\d{3}-\d{3}-\d{4}/, ‘xxx-xxx-xxxx‘)
  expect(result).toEqual(expected)
}

function globalRegexReplace() {
  var input = ‘The basketball is round, and the basketball is bouncy‘
  var expected = ‘The soccerball is round, and the soccerball is bouncy‘
  
  var result = input.replace(/basketball/ig, ‘soccerball‘)
  expect(result).toEqual(expected)
}

function regexReplaceGroup() {
  var input = ‘Search with [Google](https://google.com), tweet with [Twitter](https://twitter.com)‘
  var expected = ‘Search with <a href="https://google.com">Google</a>, tweet with <a href="https://twitter.com">Twitter</a>‘
  
  var result = input.replace(/\[(.*?)\]\((.*?)\)/g, ‘<a href="$2">$1</a>‘)
  expect(result).toEqual(expected)
}

function advancedRegexReplaceGroup() {
  var input = ‘foobarbaz‘
  var expected = ‘foofoo-bar-$-bazbaz‘
  
  var result = input.replace(‘bar‘, ‘$`-$&-$$-$\‘‘)
  expect(result).toEqual(expected)
}


function simpleFunctionReplacer() {
  var input = ‘theAnswerToLifeTheUniverseAndEverything‘
  var expected = ‘the-answer-to-life-the-universe-and-everything‘
  
  var result = input.replace(/[A-Z]/g, upperToHyphenLower)
  expect(result).toEqual(expected)
  
  function upperToHyphenLower(match) {
    return ‘-‘ + match.toLowerCase();
  }
}

function regexFunctionReplacerGroup() {
  var input = ‘These are the replacer arguments‘
  var expected = ‘These are the replacer arguments: replacer, arguments, 14, These are the replacer arguments‘
  
  var result = input.replace(/(replacer) (arguments)/, replacer)
  
  expect(result).toEqual(expected)
  
  function replacer(match, group1, group2, offset, wholeString) {
    return match + ‘: ‘ + [group1, group2, offset, wholeString].join(‘, ‘)
  }
}




console.clear()

simpleStringReplace()
simpleRegexReplace()
globalRegexReplace()
regexReplaceGroup()
advancedRegexReplaceGroup()
simpleFunctionReplacer()
regexFunctionReplacerGroup()

console.log(‘Tests passed‘)


function simpleStringReplace() {
  var input = ‘Perl is the best programming language‘
  var expected = ‘JavaScript is the best programming language‘
  
  var result = input.replace(‘Perl‘, ‘JavaScript‘)
  expect(result).toEqual(expected)
}

function simpleRegexReplace() {
  var input = ‘My phone number is 123-555-3344‘
  var expected = ‘My phone number is xxx-xxx-xxxx‘
  
  var result = input.replace(/\d{3}-\d{3}-\d{4}/, ‘xxx-xxx-xxxx‘)
  expect(result).toEqual(expected)
}

function globalRegexReplace() {
  var input = ‘The basketball is round, and the basketball is bouncy‘
  var expected = ‘The soccerball is round, and the soccerball is bouncy‘
  
  var result = input.replace(/basketball/ig, ‘soccerball‘)
  expect(result).toEqual(expected)
}

function regexReplaceGroup() {
  var input = ‘Search with [Google](https://google.com), tweet with [Twitter](https://twitter.com)‘
  var expected = ‘Search with <a href="https://google.com">Google</a>, tweet with <a href="https://twitter.com">Twitter</a>‘
  
  var result = input.replace(/\[(.*?)\]\((.*?)\)/g, ‘<a href="$2">$1</a>‘)
  expect(result).toEqual(expected);

// $2 --> (.*?) --> (https://google.com)
// $1 --> [.*?] --> [Google]
}

function advancedRegexReplaceGroup() {
  var input = ‘foobarbaz‘
  var expected = ‘foofoo-bar-$-bazbaz‘
  
  var result = input.replace(‘bar‘, ‘$`-$&-$$-$\‘‘)
  expect(result).toEqual(expected)
}


function simpleFunctionReplacer() {
  var input = ‘theAnswerToLifeTheUniverseAndEverything‘
  var expected = ‘the-answer-to-life-the-universe-and-everything‘
  
  var result = input.replace(/[A-Z]/g, upperToHyphenLower)
  expect(result).toEqual(expected)
  
  function upperToHyphenLower(match) {
    return ‘-‘ + match.toLowerCase();
  }
}

function regexFunctionReplacerGroup() {
  var input = ‘These are the replacer arguments‘
  var expected = ‘These are the replacer arguments: replacer, arguments, 14, These are the replacer arguments‘
  
  var result = input.replace(/(replacer) (arguments)/, replacer)
  
  expect(result).toEqual(expected)
  
  function replacer(match, group1, group2, offset, wholeString) {
    return match + ‘: ‘ + [group1, group2, offset, wholeString].join(‘, ‘)
  }
}