truncate a string in the middle with javascript

Question

anyone have a handy method to truncate a string in the middle? Something like:

truncate ('abcdefghi', 8);

would result in

'abc...hi'

UPDATE:

to be a bit more complete

• if the string is <= maxLength, return the string
• otherwise, return a version of the string that is maxLength, with a chunk taken out of the middle, and replaced with "...".
• count the three characters of "..." in the total, so if maxLength is 8, you'll only see 5 characters from the original string

Answer 1

Something like this...

function truncate(text, startChars, endChars, maxLength) {
    if (text.length > maxLength) {
        var start = text.substring(0, startChars);
        var end = text.substring(text.length - endChars, text.length);
        while ((start.length + end.length) < maxLength)
        {
            start = start + '.';
        }
        return start + end;
    }
    return text;
}
alert(truncate('abcdefghi',2,2,8));

Or to limit to true ellipsis:

function truncate(text, startChars, endChars, maxLength) {
    if (text.length > maxLength) {
        var start = text.substring(0, startChars);
        var end = text.substring(text.length - endChars, text.length);
        return start + '...' + end;
    }
    return text;
}
alert(truncate('abcdefghi',2,2,8));

jsFiddle

Answer 2

Here's one way to do it chopping up the string with substr:

var truncate = function (fullStr, strLen, separator) {
    if (fullStr.length <= strLen) return fullStr;

    separator = separator || '...';

    var sepLen = separator.length,
        charsToShow = strLen - sepLen,
        frontChars = Math.ceil(charsToShow/2),
        backChars = Math.floor(charsToShow/2);

    return fullStr.substr(0, frontChars) + 
           separator + 
           fullStr.substr(fullStr.length - backChars);
};

See example →