javascript如何使用bind指定接收者

var json = {
jArray: [],
jPush: function (c) {
this.jArray.push(c);
}
}
var examp = ["123", "~", "456"];

examp.forEach(json.jPush);

examp.forEach(json.jPush,json);
alert(json.jArray);//结果正常了是,123~456

examp.forEach(function (c) {
json.jPush(c);
});
alert(json.jArray);//123~456

examp.forEach(json.jPush.bind(json));
alert(json.jArray);