如何使用javascript更改img标签的src属性?

<img src="../template/edit.png" name="edit-save" alt="Edit" />

首先，我有一个默认的src是“../template/edit.png”，我想用“../template/save.png”onclick更改它。

更新: 这是我的HTML onclick:

<a href="#" onclick="edit()"><img src="../template/edit.png" id="edit-save" alt="Edit" /></a>

和我的JS

function edit()
{   
    var inputs = document.myform;
    for(var i = 0; i < inputs.length; i++) {
        inputs[i].disabled = false;
    }
}

我已经尝试在edit()中插入这个，它可以工作，但需要单击图像两次

var edit_save = document.getElementById("edit-save");
    edit_save.onclick = function(){
       this.src = "../template/save.png";
    }

谁能给我一些示例源代码，显示如何从JavaScript本地连接到SQL Server 2005数据库?我正在我的桌面上学习网络编程。

或者我需要使用其他脚本语言吗?建议一些替代方案，如果你有，但我现在试图用JavaScript做到这一点。我的SQL Server是本地安装在我的桌面- SQL Server Management Studio 2005和IE7浏览器。

数组初始化有一个很好的数组初始化列表。我有一个

int array[100] = {-1};

期望它充满-1，但它不是，只有第一个值是，其余都是0和随机值的混合。

的代码

int array[100] = {0};

工作很好，并将每个元素设置为0。

我错过了什么…如果值不为零，就不能初始化它吗?

和2:是默认的初始化(如上所述)比通常的循环通过整个数组和赋值还是做同样的事情?

我有个问题，我不知道怎么解决。 在我的react组件中，我在底部显示了一个很长的数据列表和一些链接。 点击任何链接后，我在列表中填充了新的链接集合，需要滚动到顶部。

问题是-如何滚动到顶部后，新的集合呈现?

'use strict';

// url of this component is #/:checklistId/:sectionId

var React = require('react'),
  Router = require('react-router'),
  sectionStore = require('./../stores/checklist-section-store');


function updateStateFromProps() {
  var self = this;
  sectionStore.getChecklistSectionContent({
    checklistId: this.getParams().checklistId,
    sectionId: this.getParams().sectionId
  }).then(function (section) {
    self.setState({
      section,
      componentReady: true
    });
  });

    this.setState({componentReady: false});
 }

var Checklist = React.createClass({
  mixins: [Router.State],

  componentWillMount: function () {
    updateStateFromProps.call(this);
  },

  componentWillReceiveProps(){
    updateStateFromProps.call(this);
   },

render: function () {
  if (this.state.componentReady) {
    return(
      <section className='checklist-section'>
        <header className='section-header'>{ this.state.section.name }   </header>
        <Steps steps={ this.state.section.steps }/>
        <a href=`#/${this.getParams().checklistId}/${this.state.section.nextSection.Id}`>
          Next Section
        </a>
      </section>
    );
    } else {...}
  }
});

module.exports = Checklist;

每次我运行rails 4.0服务器时，都会得到这样的输出。

Started GET "/" for 127.0.0.1 at 2013-11-06 23:56:36 -0500

PG::ConnectionBad - could not connect to server: Connection refused
Is the server running on host "localhost" (::1) and accepting
TCP/IP connections on port 5432?
could not connect to server: Connection refused
Is the server running on host "localhost" (127.0.0.1) and accepting
TCP/IP connections on port 5432?
could not connect to server: Connection refused
Is the server running on host "localhost" (fe80::1) and accepting
TCP/IP connections on port 5432?
:
 activerecord (4.0.0) lib/active_record/connection_adapters/postgresql_adapter.rb:825:in `connect'
 activerecord (4.0.0) lib/active_record/connection_adapters/postgresql_adapter.rb:542:in `initialize'
 activerecord (4.0.0) lib/active_record/connection_adapters/postgresql_adapter.rb:41:in `postgresql_connection'
 activerecord (4.0.0) lib/active_record/connection_adapters/abstract/connection_pool.rb:440:in `new_connection'
 activerecord (4.0.0) lib/active_record/connection_adapters/abstract/connection_pool.rb:450:in `checkout_new_connection'
 activerecord (4.0.0) lib/active_record/connection_adapters/abstract/connection_pool.rb:421:in `acquire_connection'
 activerecord (4.0.0) lib/active_record/connection_adapters/abstract/connection_pool.rb:356:in `block in checkout'
 /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/monitor.rb:211:in `mon_synchronize'
 activerecord (4.0.0) lib/active_record/connection_adapters/abstract/connection_pool.rb:355:in `checkout'
 activerecord (4.0.0) lib/active_record/connection_adapters/abstract/connection_pool.rb:265:in `block in connection'
 /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/monitor.rb:211:in `mon_synchronize'
 activerecord (4.0.0) lib/active_record/connection_adapters/abstract/connection_pool.rb:264:in `connection'
 activerecord (4.0.0) lib/active_record/connection_adapters/abstract/connection_pool.rb:546:in `retrieve_connection'
 activerecord (4.0.0) lib/active_record/connection_handling.rb:79:in `retrieve_connection'
 activerecord (4.0.0) lib/active_record/connection_handling.rb:53:in `connection'
 activerecord (4.0.0) lib/active_record/migration.rb:792:in `current_version'
 activerecord (4.0.0) lib/active_record/migration.rb:800:in `needs_migration?'
 activerecord (4.0.0) lib/active_record/migration.rb:379:in `check_pending!'
 activerecord (4.0.0) lib/active_record/migration.rb:366:in `call'
 actionpack (4.0.0) lib/action_dispatch/middleware/callbacks.rb:29:in `block in call'
 activesupport (4.0.0) lib/active_support/callbacks.rb:373:in `_run__1613334440513032208__call__callbacks'
 activesupport (4.0.0) lib/active_support/callbacks.rb:80:in `run_callbacks'
 actionpack (4.0.0) lib/action_dispatch/middleware/callbacks.rb:27:in `call'
 actionpack (4.0.0) lib/action_dispatch/middleware/reloader.rb:64:in `call'
 actionpack (4.0.0) lib/action_dispatch/middleware/remote_ip.rb:76:in `call'
 better_errors (0.9.0) lib/better_errors/middleware.rb:84:in `protected_app_call'
 better_errors (0.9.0) lib/better_errors/middleware.rb:79:in `better_errors_call'
 better_errors (0.9.0) lib/better_errors/middleware.rb:56:in `call'
 actionpack (4.0.0) lib/action_dispatch/middleware/debug_exceptions.rb:17:in `call'
 actionpack (4.0.0) lib/action_dispatch/middleware/show_exceptions.rb:30:in `call'
 railties (4.0.0) lib/rails/rack/logger.rb:38:in `call_app'
 railties (4.0.0) lib/rails/rack/logger.rb:21:in `block in call'
 activesupport (4.0.0) lib/active_support/tagged_logging.rb:67:in `block in tagged'
 activesupport (4.0.0) lib/active_support/tagged_logging.rb:25:in `tagged'
 activesupport (4.0.0) lib/active_support/tagged_logging.rb:67:in `tagged'
 railties (4.0.0) lib/rails/rack/logger.rb:21:in `call'
 quiet_assets (1.0.2) lib/quiet_assets.rb:18:in `call_with_quiet_assets'
 actionpack (4.0.0) lib/action_dispatch/middleware/request_id.rb:21:in `call'
 rack (1.5.2) lib/rack/methodoverride.rb:21:in `call'
 rack (1.5.2) lib/rack/runtime.rb:17:in `call'
 activesupport (4.0.0) lib/active_support/cache/strategy/local_cache.rb:83:in `call'
 rack (1.5.2) lib/rack/lock.rb:17:in `call'
 actionpack (4.0.0) lib/action_dispatch/middleware/static.rb:64:in `call'
 railties (4.0.0) lib/rails/engine.rb:511:in `call'
 railties (4.0.0) lib/rails/application.rb:97:in `call'
 rack (1.5.2) lib/rack/content_length.rb:14:in `call'
 thin (1.5.1) lib/thin/connection.rb:81:in `block in pre_process'
 thin (1.5.1) lib/thin/connection.rb:79:in `pre_process'
 thin (1.5.1) lib/thin/connection.rb:54:in `process'
 thin (1.5.1) lib/thin/connection.rb:39:in `receive_data'
 eventmachine (1.0.3) lib/eventmachine.rb:187:in `run'
 thin (1.5.1) lib/thin/backends/base.rb:63:in `start'
 thin (1.5.1) lib/thin/server.rb:159:in `start'
 rack (1.5.2) lib/rack/handler/thin.rb:16:in `run'
 rack (1.5.2) lib/rack/server.rb:264:in `start'
 railties (4.0.0) lib/rails/commands/server.rb:84:in `start'
 railties (4.0.0) lib/rails/commands.rb:78:in `block in <top (required)>'
 railties (4.0.0) lib/rails/commands.rb:73:in `<top (required)>'
 bin/rails:4:in `<main>'

我运行的是Mavericks OS X 10.9，所以我不知道这是否是问题所在。我已经尽力了，但似乎都没用。我已经卸载和安装postgres和pg gem多次了。

这是我的数据库。yml文件

development:
  adapter: postgresql
  encoding: unicode
  database: metals-directory_development
  pool: 5
  username: 
  password: 
  template: template0
  host: localhost
  port: 5432

test: &test
  adapter: postgresql
  encoding: unicode
  database: metals-directory_test
  pool: 5
  username: 
  password: 
  template: template0
  host: localhost
  port: 5432

staging:
  adapter: postgresql
  encoding: unicode
  database: metals-directory_production
  pool: 5
  username:
  password:
  template: template0
  host: localhost

production:
  adapter: postgresql
  encoding: unicode
  database: metals-directory_production
  pool: 5
  username:
  password:
  template: template0
  host: localhost

cucumber:
  <<: *test

我想知道如何在jinja中用另一个变量设置一个变量。我会解释，我有一个子菜单，我想显示哪个链接是活跃的。我试了一下:

{% set active_link = {{recordtype}} -%}

其中recordtype是为模板给定的变量。

在用cocoapods安装RestKit之后，我遇到了一个奇怪的问题。 在用cocoapods解决我的项目的RestKit依赖关系并试图构建它之后，我面临这个错误:

沙箱与Podfile.lock不同步。运行“pod install”或更新CocoaPods安装。

我试着运行pod安装，但没有变化。

以下是一些照片:

  PODS:
  - AFNetworking (1.3.3)
  - RestKit (0.20.3):
    - RestKit/Core
  - RestKit/Core (0.20.3):
    - RestKit/CoreData
    - RestKit/Network
    - RestKit/ObjectMapping
  - RestKit/CoreData (0.20.3)
  - RestKit/Network (0.20.3):
    - AFNetworking (~> 1.3.0)
    - RestKit/ObjectMapping
    - RestKit/Support
    - SOCKit
  - RestKit/ObjectMapping (0.20.3)
  - RestKit/Search (0.20.3):
    - RestKit/CoreData
  - RestKit/Support (0.20.3):
    - TransitionKit (= 1.1.1)
  - RestKit/Testing (0.20.3)
  - SOCKit (1.1)
  - TransitionKit (1.1.1)

DEPENDENCIES:
  - RestKit (~> 0.20.0)
  - RestKit/Search (~> 0.20.0)
  - RestKit/Testing (~> 0.20.0)

SPEC CHECKSUMS:
  AFNetworking: 61fdd49e2ffe6380378df37b3b6e70630bb9dd66
  RestKit: 1f181c180105a92f11ec4f6cd7de37625e516d83
  SOCKit: 2f3bc4d07910de12dcc202815e07db68a3802581
  TransitionKit: d0e3344aac92991395d4c2e72d9c5a8ceeb12910

COCOAPODS: 0.29.0

我使用node-mongodb-native驱动与MongoDB写一个网站。

我有一些关于如何管理连接的问题:

Is it enough using only one MongoDB connection for all requests? Are there any performance issues? If not, can I setup a global connection to use in the whole application? If not, is it good if I open a new connection when request arrives, and close it when handled the request? Is it expensive to open and close a connection? Should I use a global connection pool? I hear the driver has a native connection pool. Is it a good choice? If I use a connection pool, how many connections should be used? Are there other things I should notice?

PostgreSQL中是否有一个命令来选择到给定数据库的活动连接?

psql声明我不能删除我的一个数据库，因为有到它的活动连接，所以我想看看连接是什么(以及来自哪些机器)

我需要将程序的输出分配给使用MS批处理文件的变量。

所以在GNU Bash shell中，我将使用VAR=$(应用程序arg0 arg1)。我需要在Windows中使用批处理文件的类似行为。

比如set VAR=application arg0 arg1。

类似的问题

如何在批处理文件中将命令输出设置为变量 我如何得到一个命令的结果在一个变量在窗口? 在Windows批处理文件中使用命令的结果设置变量的值 将命令的输出设置为变量(使用管道) 将命令输出分配给批处理文件中的变量