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

'use strict';

var eaw = require('eastasianwidth');

function stringWidth (config) {
    var ambiguousCharWidth = (config && config.ambiguousEastAsianCharWidth) || 1;
    return function widthOf (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 += ambiguousCharWidth;
                break;
            }
        }
        return width;
    };
}

module.exports = stringWidth;