Sketch Script to crop text to remove whitespace on the line.

SketchPlugin-Text-Crop.js

var doc = context.document
var Text = require('sketch/dom').Text
var page = MSDocument.currentDocument().currentPage();


var fontFamilies = ['Monaco','Helvetica-Black']


fontFamilies.forEach(fam => {console.log(getCropsForFontFamily(fam))})

function getCropsForFontFamily(fontFamily){
let family = fontFamily
let size = 16


var text = new Text({
text: "T",
parent: page
})

var predicate = NSPredicate.predicateWithFormat("objectID == %@", text.id)
var result = page.children().filteredArrayUsingPredicate(predicate);
let textLayer = result[0]
textLayer.fontPostscriptName = family
textLayer.fontSize = size
let defaultLineHeight = getDefaultLineHeightForFont(textLayer.fontPostscriptName(),textLayer.fontSize())
let defaultLineHeightEm = defaultLineHeight/size


let bounds = textLayer.pathInFrame().bounds()
let t = -bounds.origin.y/size
let b = -((defaultLineHeight-bounds.size.height)-bounds.origin.y)/size

text.remove()

return {'family':fontFamily,'top':t,'bottom':b,'defaultLineHeight':defaultLineHeightEm}
}


function getDefaultLineHeightForFont(fontFamily, size) {
    let font = NSFont.fontWithName_size(fontFamily, size);
    let lm = NSLayoutManager.alloc().init();
    return lm.defaultLineHeightForFont(font);
}