a javascript Object reference bug

Question

I meet a bug like this:

    let     needUploadFiles: string[] = [],
            needUploadPages: Filmstrip[] =[],
            needUploadContents: string[] = [];


        Win.dataSource.filmstrips.forEach((filmstrip: Filmstrip, index) => {

            if (Page.pages[index]) {
                filmstrip.content = Page.pages[index].cleanHTML();
            }   

            let hash = Lib.sha1(filmstrip.content),
                content: string = filmstrip.content;

            if (filmstrip.hash != hash) {
                needUploadFiles.push(hash);
                needUploadPages.push(filmstrip);
                needUploadContents.push(content);

            }

        });

Promise.uploadFiles(
                needUploadFiles, needUploadContents,
                (hash: string, index: number) => {
                    needUploadPages[index].hash = hash;
                }
            );

I want change Win.dataSource.filmstrips.hash;

usually it ok.

but sometimes needUploadPages[index].hash can not change Win.dataSource

I add console in Promise.uploadFiles like:

i change Win.dataSource.filmstrips,

make Win.dataSource.filmstrips.length = 1 to check;

When a bug occurs :

Promise.uploadFiles(
                    needUploadFiles, needUploadContents,
                    (hash: string, index: number) => {
                        console.log(hash);
                        needUploadPages[index].hash = hash;
                        console.log(needUploadPages[index].hash == hash)//true
                        console.log(Win.dataSource.filmstrips[index].hash == hash)//false
                        console.log(Win.dataSource.filmstrips[index] === needUploadPages[index])// false
                    }
                );

then i changed like this:

            let needUploadPages: Filmstrip[] =[],
            needUploadContents: string[] = [],
            needUploadIndex: number[] = [];

        Win.dataSource.filmstrips.forEach((filmstrip: Filmstrip, index) => {

            if (Page.pages[index]) {
                filmstrip.content = Page.pages[index].cleanHTML();
            }   

            let hash = Lib.sha1(filmstrip.content),
                content: string = filmstrip.content;

            if (filmstrip.hash != hash) {

                needUploadPages.push(filmstrip);
                needUploadContents.push(content);
                needUploadIndex.push(index);
            }

        });

Promise.uploadFiles(
                needUploadFiles, needUploadContents,
                (hash: string, index: number) => {

               Win.dataSource.filmstrips[needUploadIndex[index]].hash = hash;

                }
            );

it not bug.

I don't know why.

why sometime is right sometime false;

I hope get this answer.

thank you guys,

My English is not good，sorry.

Please show your actual code. `.push[data]` and `.push[index]` both do nothing. — Ry-, Apr 12 '18 at 07:34
hi Ry, i changed my question,Can you help me find where problem in it? — zhaoxuan du, Apr 12 '18 at 09:12

score 0 · Accepted Answer · answered Apr 12 '18 at 08:10

0

Object references work fine. Try this simple example:

const origObjects = [{a: 1}, {a: 2}, {a: 3}]
const newObjects = []

origObjects.forEach(obj => newObjects.push(obj))
newObjects[1].a = 55
console.log(origObjects[1]) // Results in {a: 55}

I would say you have an error somewhere in the arrays and indexes. Try console.log the arrays and compare them whether they have the same content.

answered Apr 12 '18 at 08:10

Jan Steuer

141
4

thank you.but when Win.dataSource.filmstrips.length = 1 ,also had this bug,i had edit this question and add console. – zhaoxuan du Apr 12 '18 at 08:28
Try print `console.log(Win.dataSource.filmstrips[index])` and `console.log(needUploadPages[index])` whether there isn't some nonsense in one of the arrays. – Jan Steuer Apr 12 '18 at 08:56
@ Jan Steuer, thank you i try. but only diffrent on hash. – zhaoxuan du Apr 12 '18 at 09:07
And what is `Win.dataSource`? Don't you reload it somewhere? Because it would create new objects. Try to update the hash in the `forEach` and compare it there. – Jan Steuer Apr 12 '18 at 09:19

a javascript Object reference bug

1 Answers1