Javascript 使用Javascript检查字符串是否以http开头
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Check if a string starts with http using Javascript
提问by Peter
I've been searching all over for an answer to this and all of the answers I've found haven't been in JavaScript.
我一直在寻找这个问题的答案，而我找到的所有答案都没有出现在 JavaScript 中。
I need a way, in javascript, to check if a string starts with http, https, or ftp. If it doesn't start with one of those I need to prepend the string with http://. indexOf won't work for me I don't think as I need either http, https or ftp. Also I don't want something like google.com/?q=http://google.comto trigger that as being valid as it doesn't start with an http whereas indexOf would trigger that as being true (if I'm not entirely mistaken).
我需要一种在 javascript 中检查字符串是否以 http、https 或 ftp 开头的方法。如果它不是以其中之一开头，我需要在字符串前加上http://. indexOf 对我不起作用我认为不需要，因为我需要 http、https 或 ftp。此外，我不希望google.com/?q=http://google.com触发它是有效的，因为它不是以 http 开头，而 indexOf 会触发它为真（如果我没有完全弄错的话）。
The closest PHP regex I've found is this:
我发现的最接近的 PHP 正则表达式是这样的：
function addhttp($url) {
if (!preg_match("~^(?:f|ht)tps?://~i", $url)) {
$url = "http://" . $url;
}
return $url;
}
Source: How to add http if its not exists in the url
来源：如果 http 不存在于 url 中，如何添加 http
I just don't know how to convert that to javascript. Any help would be greatly appreciated.
我只是不知道如何将其转换为 javascript。任何帮助将不胜感激。
回答by user123444555621
export const getValidUrl = (url = "") => {
let newUrl = window.decodeURIComponent(url);
newUrl = newUrl.trim().replace(/\s/g, "");
if(/^(:\/\/)/.test(newUrl)){
return `http${newUrl}`;
}
if(!/^(f|ht)tps?:\/\//i.test(newUrl)){
return `http://${newUrl}`;
}
return newUrl;
};
Tests:
测试：
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');
回答by tskuzzy
回答by nicowernli
var url = "http://something.com"
if( url.indexOf("http") == 0 ) {
alert("yeah!");
} else {
alert("No no no!");
}
回答by elclanrs
This should work:
这应该有效：
var re = /^(http|https|ftp)/
回答by Steven Spungin
Refining previous answers a bit more, I used new RegExp(...)to avoid messy escapes, and also added an optional s.
进一步完善以前的答案，我曾经new RegExp(...)避免混乱的转义，并且还添加了一个可选的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'));回答by Shota
With new ES6 Features:
具有新的 ES6 特性：
export const hasValidUrlProtocol = (url) =>
Boolean(['http://', 'https://', 'ftp://'].some(protocol => url.startsWith(protocol)))
