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JavaScript to achieve the rainbow text effect method

  • 2020-05-30 19:20:06
  • OfStack

The example of this article describes how JavaScript achieves the rainbow text effect. Share with you for your reference. The details are as follows: 


<HTML>
<HEAD>
<TITLE>Rainbow Text</TITLE>
<SCRIPT LANGUAGE="JavaScript">
<!-- Begin hide from old browsers
function createHexArray(n)
{
 this.length = n;
 for (var i = 1; i <= n; i++)
 this[i] = i - 1;
 this[11] = "A";
 this[12] = "B";
 this[13] = "C";
 this[14] = "D";
 this[15] = "E";
 this[16] = "F";
 return this;
}
hx = new createHexArray(16);
function convertToHex(x)
{
 if (x < 17)
  x = 16;
 var high = x / 16;
 var s = high+"";
 s = s.substring(0, 2);
 high = parseInt(s, 10);
 var left = hx[high + 1];
 var low = x - high * 16;
 if (low < 1)
  low = 1;
 s = low + "";
 s = s.substring(0, 2);
 low = parseInt(s, 10);
 var right = hx[low + 1];
 var string = left + "" + right;
 return string;
}
function makeRainbow(text)
{
 text = text.substring(0, text.length);
 color_d1 = 255;
 mul = color_d1 / text.length;
 for(var i = 0; i < text.length; i++) {
  color_d1 = 255*Math.sin(i / (text.length / 3));
  color_h1 = convertToHex(color_d1);
  color_d2 = mul * i;
  color_h2 = convertToHex(color_d2);
  k = text.length;
  j = k - i;
  if (j < 0)
   j = 0;
  color_d3 = mul * j;
  color_h3 = convertToHex(color_d3);
  document.write("<FONT COLOR=\"#" + color_h3 + color_h1 + 
  color_h2 + "\">" + text.substring(i, i + 1) + "</FONT>");
 }
}
// End hide from old browsers -->
</script>
</HEAD>
<body bgcolor="#FFFFCC">
<center>
<strong>
<font size=6>
<script>
<!--
// change to your own text ...
makeRainbow("Welcome to Boulder City Nevada");
document.write("<br>");
makeRainbow("The best dam city in the USA");
// -->
</script>
</font>
</strong>
</center>
</body>
</html>

I hope this article has been helpful to your javascript programming.

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