String Functions In JavaScript #18 | Complete JavaScript Course | #javascript

In this video we have discuss about the topic "Strings". JavaScript String Methods String length String slice() String substring() String substr() String replace() String replaceAll() String toUpperCase() String toLowerCase() String concat() String trim() String trimStart() String trimEnd() String padStart() String padEnd() String charAt() String charCodeAt() String split() Note String search methods are covered in the next chapter. JavaScript String Length The length property returns the length of a string: Example let text = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"; let length = text.length; Extracting String Parts There are 3 methods for extracting a part of a string: slice(start, end) substring(start, end) substr(start, length) JavaScript String slice() slice() extracts a part of a string and returns the extracted part in a new string. The method takes 2 parameters: start position, and end position (end not included). Example Slice out a portion of a string from position 7 to position 13: let text = "Apple, Banana, Kiwi"; let part = text.slice(7, 13); Note JavaScript counts positions from zero. First position is 0. Second position is 1. Examples If you omit the second parameter, the method will slice out the rest of the string: let text = "Apple, Banana, Kiwi"; let part = text.slice(7); If a parameter is negative, the position is counted from the end of the string: let text = "Apple, Banana, Kiwi"; let part = text.slice(-12); This example slices out a portion of a string from position -12 to position -6: let text = "Apple, Banana, Kiwi"; let part = text.slice(-12, -6); JavaScript String substring() substring() is similar to slice(). The difference is that start and end values less than 0 are treated as 0 in substring(). Example let str = "Apple, Banana, Kiwi"; let part = str.substring(7, 13); If you omit the second parameter, substring() will slice out the rest of the string. JavaScript String substr() substr() is similar to slice(). The difference is that the second parameter specifies the length of the extracted part. Example let str = "Apple, Banana, Kiwi"; let part = str.substr(7, 6); If you omit the second parameter, substr() will slice out the rest of the string. Example let str = "Apple, Banana, Kiwi"; let part = str.substr(7); If the first parameter is negative, the position counts from the end of the string. Example let str = "Apple, Banana, Kiwi"; let part = str.substr(-4); Replacing String Content The replace() method replaces a specified value with another value in a string: Example let text = "Please visit Microsoft!"; let newText = text.replace("Microsoft", "W3Schools"); Note The replace() method does not change the string it is called on. The replace() method returns a new string. The replace() method replaces only the first match If you want to replace all matches, use a regular expression with the /g flag set. See examples below. By default, the replace() method replaces only the first match: Example let text = "Please visit Microsoft and Microsoft!"; let newText = text.replace("Microsoft", "W3Schools"); By default, the replace() method is case sensitive. Writing MICROSOFT (with upper-case) will not work: Example let text = "Please visit Microsoft!"; let newText = text.replace("MICROSOFT", "W3Schools"); To replace case insensitive, use a regular expression with an /i flag (insensitive): Example let text = "Please visit Microsoft!"; let newText = text.replace(/MICROSOFT/i, "W3Schools"); Note Regular expressions are written without quotes. To replace all matches, use a regular expression with a /g flag (global match): Example let text = "Please visit Microsoft and Microsoft!"; let newText = text.replace(/Microsoft/g, "W3Schools"); Note You will learn a lot more about regular expressions in the chapter JavaScript Regular Expressions. JavaScript String ReplaceAll() In 2021, JavaScript introduced the string method replaceAll(): Example text = text.replaceAll("Cats","Dogs"); text = text.replaceAll("cats","dogs"); The replaceAll() method allows you to specify a regular expression instead of a string to be replaced. If the parameter is a regular expression, the global flag (g) must be set, otherwise a TypeError is thrown. Example text = text.replaceAll(/Cats/g,"Dogs"); text = text.replaceAll(/cats/g,"dogs"); Note replaceAll() is an ES2021 feature. replaceAll() does not work in Internet Explorer. Converting to Upper and Lower Case A string is converted to upper case with toUpperCase(): A string is converted to lower case with toLowerCase(): #JavaScript #html #css #javascripttutorials #webdevelopment #codeschool #code #codelife #webdevelopmenttutorial

Видео String Functions In JavaScript #18 | Complete JavaScript Course | #javascript автора Фрилансерский Кодерский JS