Question

These strings may be long paragraphs, so I’m not sure it’s best to split the entire string with a space delimiter. I’m trying to get, say, the first 10 words and wrap them in a span:

'<span class="easing">' + string + '</span>'

Then rejoin that with the second half of the original split. Suggestions on a super efficient way to do this? It would affect at most three paragraphs on the page at a time.

EDITED

Here’s a kicker — The split should occur after the 9th word OR at the end of the first sentence (if that sentence is less than 9 words).

EXAMPLE

var origString = 'Coming into the world on Elvis’ birthday with a doctor named Presley seemed fortuitous until, wielding the silvery smooth scalpel in his aged unsteady hand, the doctor sliced through the walls of my mother’s uterus and into my unborn skin. Inside the warm soothing waters of my mother’s womb, inside the silent weightlessness, I was safe. Then the prick of cold steel marked the first in a series of rude awakenings. I was scarred for life even before birth.';
var newString = '<span="easing">Coming into the world on Elvis’ birthday with a doctor</span> named Presley seemed fortuitous until, wielding the silvery smooth scalpel in his aged unsteady hand, the doctor sliced through the walls of my mother’s uterus and into my unborn skin. Inside the warm soothing waters of my mother’s womb, inside the silent weightlessness, I was safe. Then the prick of cold steel marked the first in a series of rude awakenings. I was scarred for life even before birth.';

Or with a short sentence that starts the paragraph:

var origString = '“Is he okay? Tell me everything’s okay” she pleas, her desperate need to confirm my health competing with her own need for consolation.';
var newString = '<span class="easing">“Is he okay?</span> Tell me everything’s okay” she pleas, her desperate need to confirm my health competing with her own need for consolation.';

Answer 1

return string.replace(/.+?[,.?!]|.+$/, function(match, index, string){
    var words = match.split(/\s+/);
    words[ words.length<10 ? words.length-1 : 9 ] += '</span>';
    return '<span class="easing">' + words.join(" ");
});

This matches the first sentence-like thing (or the whole string – unless linebreaks), and wraps the first 10 words of it in that span. Works for both your sample inputs, but also on smaller ones. Returns the empty string for an empty string, change the regex to …|.*$ if you want an empty span.