How to use document getElementByName and getElementByTag

Question

document getElementById  frmMain   elements   can i use like this   document getElementByName  frmMain   elements    or   document getElementBytag  table   elements

User · Answer

I assume you are talking about getElementById   returning a reference to an element whilst the others return a node list  Just subscript the nodelist for the others  e g  document getElementBytag  table   4    Also  elements is only a property of a form  HTMLFormElement   not a table such as in your example

User · Answer

getElementById returns either a reference to an element with an id matching the argument  or null if no such element exists in the document   getElementsByName    note the plural Elements  returns a  possibly empty  HTMLCollection of the elements with a name matching the argument  Note that IE treats the name and id attributes and properties as the same thing  so getElementsByName will return elements with matching id also   getElementsByTagName is similar but returns a NodeList  It s all there in the relevant specifications

User · Answer

It s getElementsByName   and getElementsByTagName   - note the  s  in  Elements   indicating that both functions return a list of elements  i e   a NodeList  which you will access like an array  Note that the second function ends with  TagName  not  Tag    Even if the function only returns one element it will still be in a NodeList of length one  So   var els   document getElementsByName  frmMain       els length will be the number of elements returned    els 0  will be the first element returned    els 1  the second  etc    Assuming your form is the first  or only  form on the page you can do this   document getElementsByName  frmMain   0  elements document getElementsByTagName  table   0  elements

User · Answer

If you have given same text name for both of your Id and Name properties you can give like document getElementByName  frmMain   index  other wise object required error will come And if you have only one table in your page you can use document getElementBytag  table   index    EDIT   You can replace the index according to your form  if its first form place 0 for index

User · Answer

document getElementById  frmMain   elements assumes the form has an ID and that the ID is unique as IDs should be  Although it also accesses a name attribute in IE  please add ID to the element if you want to use getElementById      document getElementsByName  frmMain   0  elements will get the elements of the first object named frmMain on the page - notice the plural getElements - it will return a collection       document getElementsByTagName  form   0  elements will get the elements of the first form on the page based on the tag - again notice the plural getElements     A great alternative is    document querySelector  form   elements will get the elements of the first form on the page  The  form  is a valid CSS selector      document querySelectorAll  form   0  elements notice the All - it is a collection  The  0  will get the elements of the first form on the page  The  form  is a valid CSS selector   In all of the above  the  elements can be replaced by for example  querySelectorAll   type text    to get all text elements

User · Answer

The getElementsByName   method accesses all elements with the specified name  this method returns collection of elements that is an array  The getElementsByTagName   method accesses all elements with the specified tagname  this method returns collection of elements that is an array  Accesses the first element with the specified id  this method returns only a single element    eg    lt script type  text javascript  gt      function getElements             var x document getElementById  y              alert x value          lt  script gt   lt  head gt   lt body gt       lt input name  x  id  y  type  text  size  20    gt  lt br   gt    This will return a single HTML element and display the value attribute of it    lt script type  text javascript  gt      function getElements               var x document getElementsByName  x              alert x length            lt  script gt   lt  head gt   lt body gt       lt input name  x  id  y  type  text  size  20    gt  lt br   gt       lt input name  x  id  y  type  text  size  20    gt  lt br   gt    this will return an array of HTML elements and number of elements that match the name attribute   Extracted from w3schools

[javascript] How to use document.getElementByName and getElementByTag?

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