عبارت های باقاعده یا regular expression
@milad
@ali.bayat
@kianlatifi
@endworld
من میخوام با preg,matchall تگ دلخواه <a> رو بیرون بکشم یعنی در این کد ما سه تا تگ aداریم من میخوام تک a دوم رو بگیرم یا تگ a سوم رو بگیرم چطوری میتونم این کار رو انجام بدم میشه راهنمایی کنید
<p>
<a href="\"\/download\/?url=https%3A%2F%2Fwww.youtube.com%2Fapi%2Ftimedtext%3Fv%3DgAkwW2tuIqE%26asr_langs%3Dde%2Cen%2Ces%2Cfr%2Cit%2Cja%2Cko%2Cnl%2Cpt%2Cru%26caps%3Dasr%26xorp%3Dtrue%26xoaf%3D5%26hl%3Den%26ip%3D0.0.0.0%26ipbits%3D0%26expire%3D1604065133%26sparams%3Dip%2Cipbits%2Cexpire%2Cv%2Casr_langs%2Ccaps%2Cxorp%2Cxoaf%26signature%3D4DE2105D3F9F340F7DE09F57C246E90A0495759D.BA4AD77A037B8F29EBEF1D0B5AC1CAB508D972BD%26key%3Dyt8%26kind%3Dasr%26lang%3Den&title=Learn+Docker+in+7+Easy+Steps+-+Full+Beginner%27s+Tutorial\"">
</a>
<a href="\"\/download\/?url=https%3A%2F%2Fwww.youtube.com%2Fapi%2Ftimedtext%3Fv%3DgAkwW2tuIqE%26asr_langs%3Dde%2Cen%2Ces%2Cfr%2Cit%2Cja%2Cko%2Cnl%2Cpt%2Cru%26caps%3Dasr%26xorp%3Dtrue%26xoaf%3D5%26hl%3Den%26ip%3D0.0.0.0%26ipbits%3D0%26expire%3D1604065133%26sparams%3Dip%2Cipbits%2Cexpire%2Cv%2Casr_langs%2Ccaps%2Cxorp%2Cxoaf%26signature%3D4DE2105D3F9F340F7DE09F57C246E90A0495759D.BA4AD77A037B8F29EBEF1D0B5AC1CAB508D972BD%26key%3Dyt8%26kind%3Dasr%26lang%3Den%26tlang%3Daf&title=Learn+Docker+in+7+Easy+Steps+-+Full+Beginner%27s+Tutorial\""><b>Download<\/b><\/a> Afrikaans<br\><\/p>\n</br\></b>
</a>
<a href="\"\/download\/?url=https%3A%2F%2Fwww.youtube.com%2Fapi%2Ftimedtext%3Fv%3DgAkwW2tuIqE%26asr_langs%3Dde%2Cen%2Ces%2Cfr%2Cit%2Cja%2Cko%2Cnl%2Cpt%2Cru%26caps%3Dasr%26xorp%3Dtrue%26xoaf%3D5%26hl%3Den%26ip%3D0.0.0.0%26ipbits%3D0%26expire%3D1604065133%26sparams%3Dip%2Cipbits%2Cexpire%2Cv%2Casr_langs%2Ccaps%2Cxorp%2Cxoaf%26signature%3D4DE2105D3F9F340F7DE09F57C246E90A0495759D.BA4AD77A037B8F29EBEF1D0B5AC1CAB508D972BD%26key%3Dyt8%26kind%3Dasr%26lang%3Den%26tlang%3Daf&title=Learn+Docker+in+7+Easy+Steps+-+Full+Beginner%27s+Tutorial\""><b>Download<\/b><\/a> Afrikaans<br\><\/p>\n</br\></b>
</a>
</p>گزینش سوالات
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این باید پاسخ سوالتون رو نشون بده (کدها در جاوااسکریپت):
<!doctype html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport"
content="width=device-width, user-scalable=no, initial-scale=1.0, maximum-scale=1.0, minimum-scale=1.0">
<meta http-equiv="X-UA-Compatible" content="ie=edge">
<title>regex-nth-occurence</title>
<style>
#regexSel {
padding-bottom: 12px;
border-bottom: 1px solid silver
}
.btn {
display: inline-block;
padding: 8px 12px;
margin-bottom: 10px;
font-family: inherit;
font-size: 18px;
text-align: center;
text-decoration: none;
background-color: darkcyan;
color: white;
border: none;
border-radius: 4px;
transition: .2s;
cursor: pointer;
}
.btn:hover {
filter: brightness(120%);
}
</style>
</head>
<body>
<ul id="regexSel">
<li><a href="http://exam1.com" class="btn">exam1</a></li>
<li><a href="http://exam2.com" class="btn">exam2</a></li>
<li><a href="http://exam3.com" class="btn">exam3</a></li>
<li><a href="http://exam4.com" class="btn">exam4</a></li>
<li><a href="http://exam5.com" class="btn">exam5</a></li>
<li><a href="http://exam6.com" class="btn">exam6</a></li>
<li><a href="http://exam7.com" class="btn">exam7</a></li>
</ul>
<p>
answer for 3th occurence: <span id='answer'></span>
</p>
<script>
let str = document.querySelector('#regexSel').innerHTML;
// ?: for Non-capturing groups in regular expressions
// {2}: change number for (n+1)th occurence
let regexp = /(?:[\s\S]*?<a[^>]*>([^<]+)<\/a>[\s\S]*?){2}(<a[^>]*>([^<]+)<\/a>)/;
let result = str.match(regexp);
document.querySelector('#answer').innerHTML = result[2];
console.log( result.length );
console.log( result[0] );
console.log( result[1] );
console.log( result[2] ); // answer
console.log( result[3] );
console.log( result[4] );
</script>
</body>
</html>