Convert javascript string to object

convertStrToObj.js

// 临时解决方案而已 (It is not a good part code)
var convertStrToObj = function(str)
{
    var val = str.slice(1, -1);
    var properties = val.split(', ');
    var obj = {};
    properties.forEach(function(property) {
        var index = property.indexOf(':');

        var pre = property.slice(0, index).trim();
        var aft = property.slice(index + 1).trim().slice(1, -1);

        obj[pre] = aft;
    });
    return obj;
};


////////
var str = "{a: '1', b: 'abc'}";
var convertObj = convertStrToObj(str);