function alter_colors(t, l){ //t = INPUT TEXT, l = NUMBERS OF CHARACTERS
n = ''; //BLANK UNTIL "FOR LOOP"

for(i=0; i<l; i++){
f = ''+i+''; //TURNS NUMBER INTO STRING TO FIND NUMBER OF DIGITS
r = f.length-1; //USED TO GET THE ONE'S PLACE DIGIT
p = f[r]; //ONE'S PLACE DIGIT

if(p==0||p==2||p==4||p==6||p==8){
n += '<span style="color: #12495d">'+t[i]+'</span>'; //TEXT COLORS WHEN "p" IS EVEN
} else {
n += '<span style="color: #32baed">'+t[i]+'</span>'; //TEXT COLORS WHEN "p" IS ODD
}
}

$("#text").html(n); //DISPLAYS TEXT IN HTML
}
<input id="t" onKeyUp="alter_colors(this.value, this.value.length)"><br>