Let's get to the point:
The main object of accessing the control is: the document object. It corresponds to all the (subobjects) personal views of the current document respectively. And several main methods have been provided to access objects.
1.
2.
3
4
Next, I will mainly talk about the specific usage of the above methods:
one. First, let me talk about the usage.
Var obj=("ID") Worth the object according to the specified ID attribute. Returns a reference to the first object whose id attribute value is equal to ID. If the corresponding group is a group of objects, the first one of the group of objects is returned.
<input name=”a” type=”text” id=”b”/>
<input name=”b” type=”text” id=”a”/>
<input type=”button” name=”submint1” value=”text1” onclick=:”alert(("b")/>)”<input type=”button” name=”submint2” value=”text2” onclick=”alert(("a")/>)” I tested the above code in IE, entered 1 in the first text box, entered 2 in the second text, and then clicked two buttons to eat a pound. As a result, both buttons return the value of the first text box. This shows that when IE executes (elementName), the returned first name or object whose id is equal to elementName, and it is not searched based on the ID.
But on the contrary, I don't have this problem in firefox. When Firefox executes (elementName), you can only look for objects that are equal to elementName. If they do not exist, return null.
two. Let’s take a look at the usage below.
Var obj=("Name") Gets the object collection based on the value of the Name property. Returns a collection of names equal to the specified Name object. Note that what is returned here is a collection, including only one element, which is also a collection.
("name")[0?1?2?3?......] This way to get a certain element. Note that if you take a set in javascript, you can use [] or () to get a value (I passed the test, but no information is written like this).
like:
<script>
function prop()
{
var objs=("a");
alert(objs(0).value);//or alert(objs[0].value) is also correct.
}
</script>
<input type="text" name="a" value="this is textbox"/>
<input type="button" value="testing" onclick="prop()"/>
three. Usage:
Var ojbs=("Tag") is based on the set of objects based on the specified element name. Returns a collection with the Tag attribute equal to the specified Tag tag. Here is also a collection. (Similar to above)
Four. usage.
is a collection of all elements in the page. For example:
(0) Represents the first element of the page.
("txt") represents a single element and a collection element of all objects whose id or name is equal to txt on the page.
If the id or name on the page equals to txt, there is only one element (including name and id case), then the result of () is just one element, otherwise it is to get a collection. (Comprehensive the respective characteristics of the and).
You can also write this way: the same is true.
For example:
<input name=aaa value=aaa>
<input id=bbb value=bbb>
<script language=Jscript>
alert()//Fetch value according to name
alert()//Fetch value based on id
</script>
Code 2:
But the name can often be the same (such as: use checkbox to get multiple hobbies of users)
<input name=aaa value=a1>
<input name=aaa value=a2>
<input id=bbb value=bbb>
<script language=Jscript>
alert((0).value)//Show a1
alert((1).value)//Show a2
alert((0).value)//This line of code will fail
</script>
Theoretically, the IDs in a page are different. If different tags appear and have the same id, it will fail, just like this: <input id=aaa value=a1>
<input id=aaa value=a2>
<script language=Jscript>
alert()//Show undefined instead of a1 or a2
</script>
So if you encounter this situation, use the following writing method:
<input id=aaa value=aaa1>
<input id=aaa value=aaa2>
<input name=bbb value=bbb>
<input name=bbb value=bbb2>
<input id=ccc value=ccc>
<input name=ddd value=ddd>
<script language=Jscript>
alert(("aaa",0).value)
alert(("aaa",1).value)
alert(("bbb",0).value)
alert(("bbb",1).value)
alert(("ccc",0).value)
alert(("ddd",0).value)
</script>
In addition, you can determine whether the browser type is IE.
--------------------------------------------------------------------------------------------------------------------------------
--------------------------------------------------------------------------------------------------------------------------------
These two sets.all are only valid in ie, layers are only valid in nc
So you can use this method to judge different browsers.
The main object of accessing the control is: the document object. It corresponds to all the (subobjects) personal views of the current document respectively. And several main methods have been provided to access objects.
1.
2.
3
4
Next, I will mainly talk about the specific usage of the above methods:
one. First, let me talk about the usage.
Var obj=("ID") Worth the object according to the specified ID attribute. Returns a reference to the first object whose id attribute value is equal to ID. If the corresponding group is a group of objects, the first one of the group of objects is returned.
<input name=”a” type=”text” id=”b”/>
<input name=”b” type=”text” id=”a”/>
<input type=”button” name=”submint1” value=”text1” onclick=:”alert(("b")/>)”<input type=”button” name=”submint2” value=”text2” onclick=”alert(("a")/>)” I tested the above code in IE, entered 1 in the first text box, entered 2 in the second text, and then clicked two buttons to eat a pound. As a result, both buttons return the value of the first text box. This shows that when IE executes (elementName), the returned first name or object whose id is equal to elementName, and it is not searched based on the ID.
But on the contrary, I don't have this problem in firefox. When Firefox executes (elementName), you can only look for objects that are equal to elementName. If they do not exist, return null.
two. Let’s take a look at the usage below.
Var obj=("Name") Gets the object collection based on the value of the Name property. Returns a collection of names equal to the specified Name object. Note that what is returned here is a collection, including only one element, which is also a collection.
("name")[0?1?2?3?......] This way to get a certain element. Note that if you take a set in javascript, you can use [] or () to get a value (I passed the test, but no information is written like this).
like:
<script>
function prop()
{
var objs=("a");
alert(objs(0).value);//or alert(objs[0].value) is also correct.
}
</script>
<input type="text" name="a" value="this is textbox"/>
<input type="button" value="testing" onclick="prop()"/>
three. Usage:
Var ojbs=("Tag") is based on the set of objects based on the specified element name. Returns a collection with the Tag attribute equal to the specified Tag tag. Here is also a collection. (Similar to above)
Four. usage.
is a collection of all elements in the page. For example:
(0) Represents the first element of the page.
("txt") represents a single element and a collection element of all objects whose id or name is equal to txt on the page.
If the id or name on the page equals to txt, there is only one element (including name and id case), then the result of () is just one element, otherwise it is to get a collection. (Comprehensive the respective characteristics of the and).
You can also write this way: the same is true.
For example:
<input name=aaa value=aaa>
<input id=bbb value=bbb>
<script language=Jscript>
alert()//Fetch value according to name
alert()//Fetch value based on id
</script>
Code 2:
But the name can often be the same (such as: use checkbox to get multiple hobbies of users)
<input name=aaa value=a1>
<input name=aaa value=a2>
<input id=bbb value=bbb>
<script language=Jscript>
alert((0).value)//Show a1
alert((1).value)//Show a2
alert((0).value)//This line of code will fail
</script>
Theoretically, the IDs in a page are different. If different tags appear and have the same id, it will fail, just like this: <input id=aaa value=a1>
<input id=aaa value=a2>
<script language=Jscript>
alert()//Show undefined instead of a1 or a2
</script>
So if you encounter this situation, use the following writing method:
<input id=aaa value=aaa1>
<input id=aaa value=aaa2>
<input name=bbb value=bbb>
<input name=bbb value=bbb2>
<input id=ccc value=ccc>
<input name=ddd value=ddd>
<script language=Jscript>
alert(("aaa",0).value)
alert(("aaa",1).value)
alert(("bbb",0).value)
alert(("bbb",1).value)
alert(("ccc",0).value)
alert(("ddd",0).value)
</script>
In addition, you can determine whether the browser type is IE.
--------------------------------------------------------------------------------------------------------------------------------
--------------------------------------------------------------------------------------------------------------------------------
These two sets.all are only valid in ie, layers are only valid in nc
So you can use this method to judge different browsers.
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