等待foreach的执行继续下一个离子2 [英] wait the execution of foreach to continue next in ionic 2

问题描述

我正在尝试在执行for循环后使用数组列表的值。

I'm trying to use the values of an array list after executing the for loop.

我的问题是，当我运行我的应用程序时，它执行下一个函数没有等待我的循环

My problem is that when I run my application, it executes the next functions without waiting my for loop

这是我的TS代码，

convertToPDF(){
    let loader = this.loadingCtrl.create({
        content: "Generating..."
    })
    loader.present().then(_=>{
        this.TempNotesImagesList.forEach(n=>{
            this.convertToDataURLviaCanvas(n.url, "image/jpeg").then(base64Img => {
                this.images.push(base64Img);
            });
        })
    }).then(_=>{
        loader.dismiss();
        console.log(this.images); //Check images
        this.createPdfX(); //convert to PDF :D
    });

}

推荐答案

你有没有需要 convertToDataURLviaCanvas 以串行或并行方式运行？

Did you need the convertToDataURLviaCanvas to run in series or parallel?

系列：

convertToPDF() {
    let loader = this.loadingCtrl.create({
        content: "Generating..."
    });
    loader.present()
    .then( _ => this.TempNotesImagesList.reduce((p, n) => p.then(_ => this.convertToDataURLviaCanvas(n.url, "image/jpeg").then(base64Img => {
        this.images.push(base64Img);
    })), Promise.resolve())).then(_ => {
        loader.dismiss();
        console.log(this.images); //Check images
        this.createPdfX(); //convert to PDF :D
    });
}

平行：

convertToPDF() {
    let loader = this.loadingCtrl.create({
        content: "Generating..."
    });
    loader.present()
    .then( _ => Promise.all(this.TempNotesImagesList.map(n => this.convertToDataURLviaCanvas(n.url, "image/jpeg").then(base64Img => this.images.push(base64Img)))))
    .then(_ => {
        loader.dismiss();
        console.log(this.images); //Check images
        this.createPdfX(); //convert to PDF :D
    });
}

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