Internet provides us a lot of services which we can access through the respective websites. Many of times, we are need to search information on a particular topic. To perform search on Internet, we can make of search engine like Google, Yahoo, Ask, Bing etc. You must have observed the textbox available for entering the search keywords. We type the keywords and it takes us to the next page where the matched results, fetched from the server, are displayed. When we design a form in HTML to capture data from the user, we use several controls. We can also make a textbox in an HTML form which can behave like a search field and we can perform Google search.
To make such a control, we use tag in HTML within the form. It looks like a normal textbox, but it is capable in performing site search.
让我们来看一个基本的SEARCH控件程序。
示例
function show(){ s=searchForm.searchField.value; document.write("You have searched for "+s); }
这个程序将使用JavaScript代码在下一页上显示搜索到的文本。
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您可能在使用Google时注意到,默认情况下搜索框中会出现一些文本,如下所示:
示例
要做到这一点,我们可以在标签中使用PLACEHOLDER属性。让我们看一个例子。
Search for :
VALUE ATTRIBUTE
的中文翻译为:
VALUE属性
To set the default value in the search box, you can use VALUE attribute in tag.
In both the cases, the spellcheck attribute is OFF i.e. false. In this situation, it will ignore errors.
Suppose, we entered “Heaith” in the search box whereas the correct spelling is “Health”. But it is not showing any wavy line under the word.
Now let us make it true and see the results.
Example
Search for :
We can also restrict the minimum and maximum number of characters in a search field with the help of MINLENGTH and MAXLENGTH attributes. Suppose in an example, where a user has to type/search admission number for a particular institution, it can accept minimum of 4 characters and maximum of 6 characters. But if you will not put a restriction, a user can type data of any length.
Example
Type Admission Number :
It is showing an error on the page because the user has not entered the minimum length of data. And if you try to exceed its maximum limit, it won’t allow to type.