为什么我的对象只保存最后的数据

Question

I'm creating two objects, struct_one and the auxiliary struct_two for primary save a data. After adding data with the help of .push . Everything data from the struct_one array, have a last the data.

 var struct_one = { comments:[{comment:String}] }; var struct_two = {comment:String}; function taskElementWork() { this. createBlockSaveNew = function() { struct_two.comment = 1 + "RED"; struct_one.comments.push(struct_two); console.log(struct_one.comments[1].comment); // = 1RED struct_two.comment = 2 + "RED"; struct_one.comments.push(struct_two); console.log(struct_one.comments[2].comment); // = 2RED struct_two.comment = 3 + "RED"; struct_one.comments.push(struct_two); console.log(struct_one.comments[3].comment); // = 3RED console.log(struct_one.comments[1].comment); // = 3RED -> Why! } } test = new taskElementWork(); test.createBlockSaveNew(); 

Answer 1

You use the same object reference on pushing.

You could take a new object before assigning values and pushing, like

function taskElementWork() {
    var struct_two = { comment: '' };
    struct_two.comment = 1 + "RED";
    struct_one.comments.push(struct_two); 
    console.log(struct_one.comments[1].comment); // = 1RED

    struct_two = { comment: '' };
    struct_two.comment = 2 + "RED";
    struct_one.comments.push(struct_two); 
    console.log(struct_one.comments[2].comment); // = 2RED

    var struct_two = { comment: '' };
    struct_two.comment = 3 + "RED";
    struct_one.comments.push(struct_two); 
    console.log(struct_one.comments[3].comment); // = 3RED
}

A slighy better way, is to use a function for building the structure and take a parameter for the comment:

function taskElementWork() {
    function buildStructure(comment) {
        return { comment: comment };
    }

    struct_one.comments.push(buildStructure(1 + "RED")); 
    console.log(struct_one.comments[1].comment); // = 1RED

    struct_one.comments.push(buildStructure(2 + "RED")); 
    console.log(struct_one.comments[2].comment); // = 2RED

    struct_one.comments.push(buildStructure(2 + "RED")); 
    console.log(struct_one.comments[3].comment); // = 3RED
}