小编Mic*_*ill的帖子

Javascript是通过引用传递还是通过值传递？以下是Javascript:Good Parts的示例.我my对矩形函数的参数非常困惑.它实际上是undefined在函数内部重新定义的.没有原始参考.如果我从函数参数中删除它,则内部区域功能无法访问它.

是关闭吗？但是没有返回任何函数.

var shape = function (config) {
    var that = {};
    that.name = config.name || "";
    that.area = function () {
        return 0;
    };
    return that;
};
var rectangle = function (config, my) {
    my = my || {};
    my.l = config.length || 1;
    my.w = config.width || 1;
    var that = shape(config);
    that.area = function () {
        return my.l * my.w;
    };
    return that;
};
myShape = shape({
    name: "Unhnown"
}); …

尝试下载Ruby 1.9.2时,RVM遇到证书错误.看起来好像curl有证书问题,但我不知道如何绕过它.我在下面列出了确切的错误信息.

$ rvm install 1.9.2
Installing Ruby from source to: /Users/willdennis/.rvm/rubies/ruby-1.9.2-p180, this may take a while depending on your cpu(s)...

ruby-1.9.2-p180 - #fetching 
ERROR: Error running 'bunzip2 '/Users/willdennis/.rvm/archives/ruby-1.9.2-p180.tar.bz2'', please read /Users/willdennis/.rvm/log/ruby-1.9.2-p180/extract.log
ruby-1.9.2-p180 - #extracting ruby-1.9.2-p180 to /Users/willdennis/.rvm/src/ruby-1.9.2-p180
ruby-1.9.2-p180 - #extracted to /Users/willdennis/.rvm/src/ruby-1.9.2-p180
Fetching yaml-0.1.3.tar.gz to /Users/willdennis/.rvm/archives

curl: (60) SSL certificate problem, verify that the CA cert is OK. Details:
error:14090086:SSL routines:SSL3_GET_SERVER_CERTIFICATE:certificate verify failed
More details here: http://curl.haxx.se/docs/sslcerts.html

curl performs SSL certificate verification by default, using a "bundle" …

是否更好使用obj.nil?或obj == nil两者的好处是什么？

我需要为我的Javascript代码添加大约100毫秒的延迟,但我不想使用setTimeout该window对象的功能,我不想使用繁忙的循环.有没有人有什么建议？

我想从Javascript对象获取属性名称以动态构建表.例:

var obj = {'fname': 'joe', 'lname': 'smith', 'number': '34'};

for (var i = 0; i < obj.properties.length; i++) {
  alert(' name=' + obj.properties[i].name + ' value=' + obj.properties[i].value);
}

会警告:

name=fname value=joe

name=lname value=smith

name=number value=34

然后我可以使用这样的对象构建一个表:

var obj = { 'players': [ 
     { 'fname': 'joe', 'lname': 'smith', 'number': '34'} , 
     { 'fname': 'jim', 'lname': 'Hoff', 'number': '12'} , 
     { 'fname': 'jack', 'lname': 'jones', 'number': '84'}   
] };    

生产:

| fname |  lname |  number |
|-------|--------|---------|
| joe …

我想使用for each ... inNode.js(v0.4.11).

我这样使用它:

var conf = {
   index: {
      path: {
         first: "index.html",
         pattern: "index/{num}.html"
      },
      template: "index.tpl",
      limit: 8
   },
   feed: {
      path: "feed.xml",
      template: "atom.tpl",
      limit: 8
   }
}

for each (var index in conf) {
  console.log(index.path);
}

我收到以下错误:

        for each (var index in conf) {
     ^^^^

node.js:134
        throw e; // process.nextTick error, or 'error' event on first tick
        ^
SyntaxError: Unexpected identifier
    at Module._compile (module.js:397:25)
    at Object..js (module.js:408:10)
    at Module.load (module.js:334:31)
    at Function._load …

与复选框不同,用户无法在单击单选按钮后取消选择单选按钮.有没有什么办法可以使用Javascript以编程方式切换它们？这将优选不使用jQuery.

我试图用mocha测试Javascript.我有这段代码:

describe('Array', function() {
    describe('indexOf()', function() {
        it("dovrebbe tornare -1 quando l'elemento non è presente", function() {
            expect([1,2,3].indexOf(4)).to.equal(-1)
        })
    })
})

和一个test/array.js文件.摩卡安装了

$ npm install -g mocha

我跑的时候

$ mocha

我收到此错误:

$ mocha
? 

0 passing (5ms)
1 failing

1) Array indexOf() dovrebbe tornare -1 quando l'elemento non è presente:
 ReferenceError: expect is not defined
  at Context.<anonymous> (/Users/simonegentili/Desktop/Javascipt Best Practice/test/array.js:4:4)
  at Test.Runnable.run (/usr/local/lib/node_modules/mocha/lib/runnable.js:211:32)
  at Runner.runTest (/usr/local/lib/node_modules/mocha/lib/runner.js:358:10)
  at /usr/local/lib/node_modules/mocha/lib/runner.js:404:12
  at next (/usr/local/lib/node_modules/mocha/lib/runner.js:284:14)
  at /usr/local/lib/node_modules/mocha/lib/runner.js:293:7
  at next (/usr/local/lib/node_modules/mocha/lib/runner.js:237:23)
  at Object._onImmediate …

在Android上,如何listview删除列表底部显示的行？

我对铁轨很陌生,并且一直试图在没有运气的情况下整夜工作.

我已经创建了3种型号:users,businesses,和business_hours.我还添加了associations(business_hours belongs_to businesses which belongs_to users)和(user has_one business which has_many business_hours).

通过在线阅读文档,我现在需要在我的数据库表中为这些关系创建外键.如何使用Rails ActiveRecord迁移执行此操作？我正在使用PostgreSQL作为我的数据库.