substr js code example

Example 1: javascript substr vs substring

let demo = 'This is a normal sentence';

// substr 
// The substr method takes two parameters
// param 1 - the starting index to copy from a string
// param 2 - the number of characters that must be copied from the starting index

let newDemo = demo.substr(3, 5);
// newDemo would be 's is ' 

// substring
// The substring method takes 1 mandatory and 1 optional parameter
// param 1 - the starting index to copy from a string
// param 2 - (optional) the ending index that will be copied until from the starting index. 
		// - it will not include the ending index position
		// - if this param is left blank. it defualts to the rest of the string

let newDemo = demo.substring(0, 3);
// newDemo would be 'Thi'

let newDemo = demo.substring(3);
// newDemo would be 's is a normal sentence'

Example 2: js substring

// the substring method returns a string out of another string

const str = 'Mozilla';

console.log(str.substring(1, 3));
// expected output: "oz"

console.log(str.substring(2));
// expected output: "zilla"

Example 3: js get first 3 characters of string

const string = "0123456789";
console.log(string.slice(0, 2)); // "01"
console.log(string.slice(0, 8)); // "01234567"
console.log(string.slice(3, 7)); // "3456"

Example 4: substring javascript

var str = "Hello world!";
var res = str.substring(1, 4); //ell

Example 5: substr() javascript

const str = 'substr';

console.log(str.substr(1, 2)); // (1, 2): ub
console.log(str.substr(1)); // (1): ubstr

/* Percorrendo de trás para frente */
console.log(str.substr(-3, 2)); // (-3, 2): st
console.log(str.substr(-3)); // (-3): str

Example 6: js .substring

let anyString = 'Mozilla'

// Displays 'M'
console.log(anyString.substring(0, 1))
console.log(anyString.substring(1, 0))

// Displays 'Mozill'
console.log(anyString.substring(0, 6))

// Displays 'lla'
console.log(anyString.substring(4))
console.log(anyString.substring(4, 7))
console.log(anyString.substring(7, 4))

// Displays 'Mozilla'
console.log(anyString.substring(0, 7))
console.log(anyString.substring(0, 10))