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Infinitely scrollable Pascal's Triangle
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<!DOCTYPE html> | |
<html lang="en" dir="ltr"> | |
<head> | |
<meta charset="utf-8"> | |
<meta name="viewport" content="width=device-width, initial-scale=1.0"> | |
<title>Pascal's Triangle</title> | |
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.6.0/jquery.min.js" charset="utf-8"></script> | |
<script type="text/javascript"> | |
$(document).ready(function(){ | |
//First line | |
var lineZero = { | |
line: [1] | |
}; | |
//Second line | |
var lineOne = { | |
line: [1, 1], | |
prevLine: lineZero | |
}; | |
//All the lines of the triangle | |
var lines = [lineZero, lineOne]; | |
//Each line is stored with an array and a reference to the previous line | |
class Line { | |
constructor(prevLine){ | |
this.prevLine = prevLine; | |
this.i = lines.length; | |
var prevNumber = 0; | |
var currNumber = 0; | |
this.line = []; | |
for (let i = 0; i <= prevLine.line.length; ++i){ | |
currNumber = (typeof prevLine.line[i] !== 'undefined') ? prevLine.line[i] : 0; | |
prevNumber = (i !== 0) ? prevLine.line[i - 1] : 0; | |
// console.log(prevNumber); | |
this.line.push(currNumber + prevNumber); | |
} | |
} | |
} | |
function addLine(){ | |
var newLine = new Line(lines[lines.length - 1]); | |
lines.push(newLine); | |
$('#wrapper2').html($('#wrapper2').html() + `<p class="line" id="line-${newLine.i}">${lines[newLine.i].line.join(' ')}</p>`); | |
var elem = $(`#line-${newLine.i}`); | |
} | |
window.addEventListener('scroll', () => { | |
const { | |
scrollTop, | |
scrollHeight, | |
clientHeight | |
} = document.documentElement; | |
if (scrollTop + clientHeight >= scrollHeight - 36){ | |
addLine(); | |
} | |
}, { passive: true }); | |
//Initialize to page height | |
var h = $('#wrapper').outerHeight(); | |
while (h < document.documentElement.clientHeight){ | |
addLine(); | |
h = $('#wrapper').outerHeight(); | |
} | |
}); | |
</script> | |
<style> | |
p { | |
font-family: sans-serif; | |
font-size: 15px; | |
} | |
#wrapper { | |
text-align: center; | |
width: 100%; | |
margin: 0 auto; | |
} | |
#wrapper2 { | |
margin: 1rem -2rem; | |
padding: 2rem 2rem; | |
display: table; | |
} | |
.line{ | |
max-width: 100%; | |
margin: 0 auto; | |
white-space: nowrap; | |
} | |
</style> | |
</head> | |
<body> | |
<div id="wrapper"> | |
<div id="wrapper2"> | |
<p class="line">1</p> | |
<p class="line">1 1</p> | |
</div> | |
</div> | |
</body> | |
</html> |
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