power-assert-formatter/lib/string-width.js

'use strict';

var eaw = require('eastasianwidth');

module.exports = function (str) {
    var i, code, width = 0;
    for(i = 0; i < str.length; i+=1) {
        code = eaw.eastAsianWidth(str.charAt(i));
        switch(code) {
        case 'F':
        case 'W':
            width += 2;
            break;
        case 'H':
        case 'Na':
        case 'N':
            width += 1;
            break;
        case 'A':
            width += 1;
            break;
        }
    }
    return width;
};