Update: Oh, I overlooked the hidden comment. The CSS solution posted above is definitely better for the job. My answer addresses directly the problem of counting the characters that fit on one line. I'm not going to delete it as someone might actually find it useful.
It is definitely possible to get the number of characters you can fit on one line even if you have a proportional typeface. There are two ways—either use the following trick or the measureText
method of CanvasRenderingContext2D
.
var target_width = 200; // line width
var text = 'Lorem ipsum. I want to know how many chars of this text fit.';
var span = document.createElement('span');
document.body.appendChild(span);
span.style.whiteSpace = 'nowrap';
// define the style
span.style.fontFamily = 'Lucida Grande';
span.style.fontSize = '14px';
var fit = text.length;
for (var i = 0; i < fit; ++i) {
span.innerHTML += text[i];
if (span.clientWidth > target_width) {
fit = i - 1;
break;
}
}
document.body.removeChild(span);
// fit = the number of characters of the text
// that you can fit on one line
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