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1,startsWith()

Check whether the string begins with the specified character

const STR = 'JavaScript is amazing';
console.log(STR.startsWith('JavaScript')); // true
console.log(STR.startsWith('Java')); // true
console.log(STR.startsWith('javascript')); // false

// Optional location
console.log(STR.startsWith('Script', 4)); // true
console.log(STR.startsWith('SCRIPT', 4)); // false

2,endsWith()

Check whether the string ends with the specified character

  const str = 'JavaScript is amazing';

  console.log(str.endsWith('amazing')); // true
  console.log(str.endsWith('ing')); // true
  console.log(str.endsWith('Amazing')); // false

  // Optional length
  // If it is not a special case, the general length refers to the length of the string.
  console.log(str.endsWith('is', 13)); // true
  console.log(str.endsWith('i', 13)); // false
  console.log(str.endsWith('s', 13)); // true

3,includes()

Check whether the string contains the specified character

  const str = 'JavaScript is amazing';

  console.log(str.includes('Script')); // true
  console.log(str.includes('script')); // false
  console.log(str.includes('array')); // false

4,slice()

Copy parts of a string without modifying the original string

 const str = 'JavaScript is amazing';

  // The default starts at index 0
  console.log(str.slice()); // 'JavaScript is amazing'

  // Copy from Index 4
  console.log(str.slice(4)); // 'Script is amazing'

  // End replication at index 10
  console.log(str.slice(0, 10)); // 'JavaScript'

5,toUpperCase()

Converting strings to uppercase letters

const str = 'JavaScript is amazing';

console.log(str.toUpperCase()); // 'JAVASCRIPT IS AMAZING'

6,toLowerCase()

Converting strings to lowercase letters

const str = 'JavaScript is amazing';

console.log(str.toLowerCase()); // 'javascript is amazing'

7,charAt()

Returns the character at the specified position

const str = 'JavaScript is amazing';

  console.log(str.charAt()); // 'J'
  console.log(str.charAt(11)); // 'i'
  console.log(str.charAt(14)); // 'a'
  console.log(str.charAt(110)); // ''

8,split()

Splitting strings into substring arrays

  const str = 'JavaScript is amazing';
  const strNew = 'JavaScript-is-amazing';

  console.log(str.split()); // ["JavaScript is amazing"]

  // A delimiter string used to determine where to split
  console.log(str.split('S')); // ["Java", "cript is amazing"]
  console.log(str.split('is')); // ["JavaScript ", " amazing"]
  console.log(str.split(' ')); // ["JavaScript", "is", "amazing"]
  console.log(strNew.split('-')); // ["JavaScript", "is", "amazing"]

9,replace()

Replace the specified value with another value in the string, case-sensitive

  const str = 'JavaScript is amazing';

  console.log(str.replace('JavaScript', 'Node.js')); // 'Node.js is amazing'

  // replace() method case-sensitive
  console.log(str.replace('Javascript', 'Node.js')); // 'JavaScript is amazing'

  // Use regular expressions to distinguish case from case
  console.log(str.replace(/Javascript/i, 'Node.js')); // 'Node.js is amazing'

  // Replace item 1
  console.log(str.replace('a', 'A')); // 'JAvaScript is amazing'

  // Replace all eligible items
  console.log(str.replace(/a/g, 'A')); // 'JAvAScript is AmAzing'

10,repeat()

Returns a new string with multiple copies of an existing string

  const str = 'JavaScript';

  console.log(str.repeat(3)); // 'JavaScriptJavaScriptJavaScript'
  console.log(str.repeat(1)); // 'JavaScript'
  console.log(str.repeat(0)); // ''