Sketchプラグインにするまでもないけど、たまによく使うスクリプトをRun Scriptから呼び出す ref: http://qiita.com/littlebusters/items/0e6aa1ee1c276044a674

file0.js

@import '/path/to/script-file.js';

file1.js

var doc = context.document;
var sel = context.selection;
var pg = doc.pages();
var cp = doc.currentPage();

file2.js

function showClassMethods(object) {
    log(object.class().mocha().classMethods());
}
function showInstMethods(object) {
    log(object.class().mocha().instanceMethods());
}
function showMethods(object) {
    log('Class Methods:');
    log(showClassMethods(object));
    log('Instance Methods:');
    log(showInstMethods(object));
}
function showProp(object) {
    log(object.class().mocha().properties());
}
function showDict(object) {
    log(object.treeAsDictionary());
}

file3.js

log('Show Help: utHelp()');
function utHelp() {
    var output = "doc\nsel\npg\ncp\n" +
                 "showClassMethods(object)\n" +
                 "showInstMethods(object)\n" +
                 "showMethods(object)\n" +
                 "showProp(object)\n" +
                 "showDict(object)\n" +
                 "getMdImagePath()\n";
    log(output);
}

file4.js

function getMdImagePath() {
    var imagesPath = '';
    if (0 < sel.count()) {
        for (var i = sel.count() - 1; i >= 0; i--) {
            imagesPath += '![](images/' + sel[i].name() + '.png)' + "\n";
        }
    }
    log(imagesPath);
}