js check string starts with code example

Example 1: javascript word start with

const str = "Saturday night plans";
const res = str.startsWith("Sat");
console.log(res); //> true

Example 2: javascript string starts with

//checks if a string starts with a word
function startsWith(str, word) {
    return str.lastIndexOf(word, 0) === 0;
}
startsWith("Welcome to earth.","Welcome"); //true

Example 3: javascript check if string ends with

function endsWith(str, suffix) {
    return str.indexOf(suffix, str.length - suffix.length) !== -1;
}

endsWith("hello young man","man");//true
endsWith("hello young man","boy");//false

Example 4: javascript string starts with

const s = 'I am going to become a FULL STACK JS Dev with Coderslang';

console.log(s.startsWith('I am'));             // true
console.log(s.startsWith('You are'));          // false