Lesson: 17 | String Methods

Notes

The length property returns the length of a string:

let text = "I am learning JavaScript";

document.write(text.length);

Output: 24

slice() extracts a part of a string and returns the extracted part in a new string.

let str = "I am learning JavaScript";

document.write(str.slice(14,24));

Output: JavaScript

Note: JavaScript counts positions from zero. First position is 0.

If a parameter is negative, the position is counted from the end of the string.

let str = "I am learning JavaScript";

document.write(str.slice(-10));

Output: JavaScript

substring() is same as slice() but does not accept negative indexes.

let str = "I am learning JavaScript";

document.write(str.slice(5,13));

Output: learning

The replace() method replaces a specified value with another value in a string:

let text = "I am learning Apex";

document.write(text.replace("Apex", "javaScript"));

Output: I am learning JavaScript.

Note: By default, the replace() method replaces only the first match and it's case sensitive.

A string is converted to upper case with toUpperCase():

let text = "JavaScript";

document.write(text.toUpperCase());

Output: JAVASCRIPT

A string is converted to lower case with toLowerCase():

let text = "JavaScript";

document.write(text.toLowerCase());

Output: javascript

concat() joins two or more strings:

let text1 = "Will";
let text2 = "Smith";

document.write(text1.concat(" ",text2));

The trim() method removes whitespace from both sides of a string:

let txt = "    Java     Script";

document.write(txt.trim());

Output: Java Script

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