var res = str.replace("find", "replace");

const p = 'dog dog cat rat';

const regex = /dog/gi;

​

console.log(p.replace(regex, 'cow'));

//if pattern is regular expression all matches will be replaced

//output: "cow cow cat rat"

​

console.log(p.replace('dog', 'cow'));

// If pattern is a string, only the first occurrence will be replaced.

//output: "cow dog cat rat"

var str = "Please locate where 'locate' occurs!";

​

str.replace("locate", "W3Schools"); //replace only replace first match from string

str.replace(/LOCATE/i, "W3Schools"); // i makes it case insensitive

str.replace(/LOCATE/g, "W3Schools"); // g replace all matches from string rather than replacing only first

​

var string = "Javascript is fun";

var newString = string.replace("fun", "Awesome");

console.log(newString); // Javascript is Awesome

you need to be very carefull to use 'MyStringggg'.replaceAll('rep','toRep') 

for those coming from c# or java or ... 

because replace just replcaes the first occurance but if you want replace all occurances then you need to use replaceAll

//option 1

let str = 'JS will, JS will rock you!';

let newStr = str.replace('JS','JavaScript');

​

console.log(newStr);

​

//option 2

let str = 'JS will, JS will rock you!';

let newStr = str.replace(/JS/g,'JavaScript');

​

console.log(newStr);

let str = 'JS will, JS will rock you!';

let newStr = str.replace('JS','JavaScript');

​

console.log(newStr);

Code language: JavaScript (javascript)

var entrada   = "Aprenda Javascript. JavaSCRIPT e Typescript";

var resultado = entrada.replace(/script/gi, "Script");

console.log({entrada, resultado})

/* Valor retornado: 

{

   entrada: 'Aprenda Javascript. JavaSCRIPT e Typescript', 

 resultado: 'Aprenda JavaScript. JavaScript e TypeScript'

}

*/

​

// Please register your like

let str = "I like to eat, eat, eat apples and bananas";

let re = /apples|bananas/gi;

​

let newStr = str.replace(re, (match) => { 

    console.log({match}); 

    return match.toUpperCase();

});

​

console.log(newStr);