Check if a string starts with http using Javascript

Question

I\'ve been searching all over for an answer to this and all of the answers I\'ve found haven\'t been in JavaScript.

I need a way, in javascript, to check if a string sta

Answer 1

var url = "http://something.com"
if( url.indexOf("http") == 0 ) {
    alert("yeah!");
} else {
    alert("No no no!");
}

Answer 2

This should work:

var re = /^(http|https|ftp)/

Answer 3

export const getValidUrl = (url = "") => {
    let newUrl = window.decodeURIComponent(url);
    newUrl = newUrl.trim().replace(/\s/g, "");

    if(/^(:\/\/)/.test(newUrl)){
        return `http${newUrl}`;
    }
    if(!/^(f|ht)tps?:\/\//i.test(newUrl)){
        return `http://${newUrl}`;
    }

    return newUrl;
};

Tests:

expect(getValidUrl('https://www.test.com')).toBe('https://www.test.com');
expect(getValidUrl('http://www.test.com')).toBe('http://www.test.com');
expect(getValidUrl('    http   :    /  /  www.test.com')).toBe('http://www.test.com');
expect(getValidUrl('ftp://www.test.com')).toBe('ftp://www.test.com');
expect(getValidUrl('www.test.com')).toBe('http://www.test.com');
expect(getValidUrl('://www.test.com')).toBe('http://www.test.com');
expect(getValidUrl('http%3A%2F%2Fwww.test.com')).toBe('http://www.test.com');
expect(getValidUrl('www    .  test.com')).toBe('http://www.test.com');

Answer 4

This should work:

var pattern = /^((http|https|ftp):\/\/)/;

if(!pattern.test(url)) {
    url = "http://" + url;
}

jsFiddle

Answer 5

Non-Regex declarative way:

export const hasValidUrlProtocol = (url = '') => 
    Boolean(['http://', 'https://', 'ftp://'].some(protocol => url.startsWith(protocol)))

Answer 6

Refining previous answers a bit more, I used new RegExp(...) to avoid messy escapes, and also added an optional s.

var pattern = new RegExp('^(https?|ftp)://');

if(!pattern.test(url)) {
    url = "http://" + url;
}

var pattern = new RegExp('^(https?|ftp)://');


console.log(pattern.test('http://foo'));
console.log(pattern.test('https://foo'));
console.log(pattern.test('ftp://foo'));
console.log(pattern.test('bar'));