why is my 0th char not H1 in this while loop?

Question

why is my 0th char not H1 in this loop?
https://code.sololearn.com/Wc0y9IdGT5a7/#

this script is demonstrating same issue...
https://code.sololearn.com/Wx1XWgSIEpIX/#js

Why?

Answer 1

Well, you can guess what's happening, isn't it?
What about the output? are all line have same size/weight?... no: when you 'document.write' something, it will be parsed as html ^^

However, the mistake is somewhere else firsly: if you want to print the nth char of a string, you absolutly aren't in the right way! I take you second example:

var i=20;
do {
document.write(i + "<H1 />");
i++;
}
while (i<=25);

What will do this code?
Whit begining 'i' to val 20, we repeat the 'write' command until i <= 25 ( for value of i in range 20 to 25 including ).
Well so the print value at each time of executing will be the result of i + "<H1 />" which is a string: "20<H1 />" on first iteration...

Unfortunaly, '<H1 />' is not valid html... so html parser try to correct it, and display it as it understand ^^ but you get anyway the list of value of 'i' in range 20-25, one per line ( the <h1> auto-corrected tag do breaking lines ).

At no instant you write code to access string characters :P

Well, to do it, you must iterate on a string as this:

var s='<h1 />';
var i=0;
var c=s.length; // we store count of char, to not access it each time the condition below is evaluate
while ( i < c ) // 'less than' is sufficient: index start to 0, so end at ( length - 1 )
{
document.write(s[i]+'<br>'); // access to char string as an array of char, and append a html break line tag to visually see that we write it each by each char
}