title: Calculate exact character\string height in javascript
body: <p>I'm working with canvases and i can't think of any solution, or find answer on line to my problem. </p>
  
  <p>I have a font that contains symbols\characters from varies sizes - heights and width.</p>
  
  <p>I want to draw some characters (Symbols) from the font and some on top\down of the symbol.
  The problem is that I can't figure out a way to have the exact height in pixels of the character that i'm drawing, and it's causes unwanted spaces between the center symbol to the one on top\down (for getting the width of a string there is the function context.measureText(theText) ).</p>
  
  <p>for ex. lets say that i want 'X' to be my center symbol. and '-' to be on top.
  It's looks like this</p>
  
  <p>-<br/>
  x</p>
  
  <p>but now there is space between the 'X' and the '-' that i don't want.</p>
  
  <p>Can anyone help me with this ?</p>
  
  <p>Thanks</p>