Igor Garnik's questions

需要给函数传一个参数，但是这种形式的interval不起作用

playGame() {
    this.interval = setInterval(this.gameService.startLife(this.field), 
    this.timeLeft)
 }

如何将数据从组件传递到服务？

运行 gulp 时在 linux ubuntu 16.04 上工作时出错

> template@1.0.0 gulp /media/Data/GitHub/template
> gulp

sh: 1: gulp: Permission denied
npm ERR! code ELIFECYCLE
npm ERR! errno 126
npm ERR! template@1.0.0 gulp: `gulp`
npm ERR! Exit status 126
npm ERR! 
npm ERR! Failed at the template@1.0.0 gulp script.
npm ERR! This is probably not a problem with npm. There is likely 
additional logging output above.

npm ERR! A complete log of this run can be found in:
npm ERR!     /home/igor/.npm/_logs/2018-04-26T14_57_52_348Z-debug.log
igor@Usus:/media/Data/GitHub/template$ 

下面是我的 gulp 文件

var gulp = require('gulp');
var concat = require('gulp-concat');
//var uglify = require('gulp-uglify');
let uglify = require('gulp-uglify-es').default;
var sourcemaps = require('gulp-sourcemaps');
var cssmin = require('gulp-cssmin');
var del = require('del');

var paths = {
   scripts: ['js/**/*.js'],
   styles: ['css/**/*.css']
};

gulp.task('clean', function() {
 return del(['build']);
});

gulp.task('css', function() {
    return gulp.src(paths.styles)
      .pipe(concat('main.min.css'))
      .pipe(sourcemaps.init())
      .pipe(cssmin())
      .pipe(sourcemaps.write())
      .pipe(gulp.dest('build/css'));
});

gulp.task('scripts', function() { 
  return gulp.src(paths.scripts)
    .pipe(uglify()) 
    .pipe(sourcemaps.init())
    .pipe(concat('main.min.js')) 
    .pipe(sourcemaps.write())
    .pipe(gulp.dest('build/js'))
});

gulp.task('watch', function() {
  gulp.watch(paths.scripts, ['scripts']);
  gulp.watch(paths.styles, ['css']);
});

面对这样的问题，Chrome 给出了以下错误。

无法加载http://localhost:3000/cars：对预检请求的响应未通过访问控制检查：“Access-Control-Allow-Origin”标头的值“null”不等于提供的来源. 因此，Origin 'null' 不允许访问。

这是我与服务器联系的请求：

getData () {
    const url = "http://localhost:3000/cars";
    const xhr = new XMLHttpRequest();
    xhr.open("GET", url, true);
    xhr.setRequestHeader('Content-type','application/json; charset=utf-8');
    xhr.onload = function () {
         const response = JSON.parse(xhr.responseText);
         if (xhr.status == "200") {
              return response;
         } else {
              console.error(response);
         }
    };
        xhr.send();
}