underscorejs类库之_.each(list, iteratee, [context])

//遍历数组
_.each([1, 2, 3], function (element, index, list) {
    console.log(element);
});

//遍历对象
_.each({one: ‘一‘, two: ‘二‘, three: ‘三‘}, function(value, key, list){
    console.log(value);
});

//遍历字符串
_.each(‘123‘, function(element, index, list){
    console.log(element);
});

//遍历arguments
function abc(){
    _.each(arguments, function(element, index, list){
       console.log(element);
    });
}
abc(1, 2, 3);

//数组的情况
_.each([1, 2, 3], function (element, index, list) {
    console.log(element, index, list);
    //1 0 [1, 2, 3]
    //2 1 [1, 2, 3]
    //3 2 [1, 2, 3]
});

//对象的情况
_.each({one: ‘一‘, two: ‘二‘, three: ‘三‘}, function(value, key, list){
    console.log(value, key, list);
    //一 one Object {one: "一", two: "二", three: "三"}
    //二 two Object {one: "一", two: "二", three: "三"}
    //三 three Object {one: "一", two: "二", three: "三"}
});

_.each([1], function (element, index, list) {
    console.log(this); //window
});

_.each([1], function (element, index, list) {
    console.log(this); //{key: 1}
}, {key : 1});

var arr1 = _.each([1, 2, 3], function (element, index, list) {
});

var arr2 = _.each({one: ‘一‘, two: ‘二‘, three: ‘三‘}, function(element, index, list){
});
console.log(arr1); //[1, 2, 3]
console.log(arr2); //Object {one: "一", two: "二", three: "三"}

_.each(null, function (element, index, list) {
    console.log(element); //不执行
});

_.each(undefined, function (element, index, list) {
    console.log(element); //不执行
});

_.each(123, function (element, index, list) {
    console.log(element); //不执行
});

_.each(new Date(), function (element, index, list) {
    console.log(element); //不执行
});

_.each([1, 2, 3], alert); //会弹三次