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mouseenter

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O evento mouseenter é disparado quando um dispositivo de apontamento (geralmente um mouse) se move sobre um elemento (para dentro do mesmo).

Similar ao mouseover, ele se diferencia no fato de que não ocorre a fase bubble e não é disparado quando o cursor / apontador mover-se do espaço físico de um de seus descendentes para o seu próprio espaço físico.

mouseenter.png
Um evento mouseenter é enviado para cada elemento da hierarquia ao entrar neles. Aqui 4 eventos são enviados aos quatro elementos da hierarquia quando o cursor / apontador chega no Text.
mouseover.png
Um único evento mouseover é enviado ao elemento de maior profundidade na árvore DOM, a partir do qual ocorre a fase bubble e o mesmo percorre subindo na hierarquia dos elementos  até que seja cancelado por um handler ou alcance a raíz da árvore.

De acordo com a profundidade da hierarquia, a quantidade de eventos mouseenter disparados pode se tornar muito grande e causar problemas de performance significativos. Nestes casos é melhor escutar por eventos mouseover.

Combinado ao comportamento do seu evento simétrico, mouseleave, o evento DOM mouseenter age de modo bastante similar à pseudo-classe CSS :hover.

Informações Gerais

Especificação
DOM L3
Interface
MouseEvent
Sincronismo
Síncrono
Fase Bubble
Não
Cancelável
Não
Target
Element
Ação Padrão
Nenhuma

Propriedades

Property Type Description
target Somente leitura EventTarget The event target (the topmost target in the DOM tree).
type Somente leitura DOMString The type of event.
bubbles Somente leitura Boolean Whether the event normally bubbles or not
cancelable Somente leitura Boolean Whether the event is cancellable or not?
view Somente leitura WindowProxy document.defaultView (window of the document)
detail Somente leitura long (float) 0.
currentTarget Somente leitura EventTarget The node that had the event listener attached.
relatedTarget Somente leitura EventTarget For mouseover, mouseout, mouseenter and mouseleave events: the target of the complementary event (the mouseleave target in the case of a mouseenter event). null otherwise.
screenX Somente leitura long The X coordinate of the mouse pointer in global (screen) coordinates.
screenY Somente leitura long The Y coordinate of the mouse pointer in global (screen) coordinates.
clientX Somente leitura long The X coordinate of the mouse pointer in local (DOM content) coordinates.
clientY Somente leitura long The Y coordinate of the mouse pointer in local (DOM content) coordinates.
button Somente leitura unsigned short The button number that was pressed when the mouse event was fired: Left button=0, middle button=1 (if present), right button=2. For mice configured for left handed use in which the button actions are reversed the values are instead read from right to left.
buttons Somente leitura unsigned short The buttons being pressed when the mouse event was fired: Left button=1, Right button=2, Middle (wheel) button=4, 4th button (typically, "Browser Back" button)=8, 5th button (typically, "Browser Forward" button)=16. If two or more buttons are pressed, returns the logical sum of the values. E.g., if Left button and Right button are pressed, returns 3 (=1 | 2). More info.
mozPressure Somente leitura float The amount of pressure applied to a touch or tabdevice when generating the event; this value ranges between 0.0 (minimum pressure) and 1.0 (maximum pressure).
ctrlKey Somente leitura boolean true if the control key was down when the event was fired. false otherwise.
shiftKey Somente leitura boolean true if the shift key was down when the event was fired. false otherwise.
altKey Somente leitura boolean true if the alt key was down when the event was fired. false otherwise.
metaKey Somente leitura boolean true if the meta key was down when the event was fired. false otherwise.

Examples

The mouseover documentation has an example illustrating the difference between mouseover and mouseenter.

The following example illustrates how to use mouseover to simulate the principle of event delegation for the mouseenter event.

<ul id="test">
  <li>
    <ul class="enter-sensitive">
      <li>item 1-1</li>
      <li>item 1-2</li>
    </ul>
  </li>
  <li>
    <ul class="enter-sensitive">
      <li>item 2-1</li>
      <li>item 2-2</li>
    </ul>
  </li>
</ul>

<script>
  var delegationSelector = ".enter-sensitive";

  document.getElementById("test").addEventListener("mouseover", function( event ) {
    var target = event.target,
        related = event.relatedTarget,
        match;

    // search for a parent node matching the delegation selector
    while ( target && target != document && !( match = matches( target, delegationSelector ) ) ) {
        target = target.parentNode;
    }

    // exit if no matching node has been found
    if ( !match ) { return; }

    // loop through the parent of the related target to make sure that it's not a child of the target
    while ( related && related != target && related != document ) {
        related = related.parentNode;
    }

    // exit if this is the case
    if ( related == target ) { return; }

    // the "delegated mouseenter" handler can now be executed
    // change the color of the text
    target.style.color = "orange";
    // reset the color after a small amount of time
    setTimeout(function() {
        target.style.color = "";
    }, 500);
    

  }, false);
 

  // function used to check if a DOM element matches a given selector
  // the following code can be replaced by this IE8 compatible function: https://gist.github.com/2851541
  function matches( elem, selector ){
    // the matchesSelector is prefixed in most (if not all) browsers
    return elem.matchesSelector( selector );
  };
</script>

Browser compatibility

Feature Chrome Edge Firefox (Gecko) Internet Explorer Opera Safari
Basic support 30[1] (Yes) 10[2] 5.5 (Yes)
Não suportado 15.0
17.0
7[3]
On disabled form elements Não suportado Não suportado 44.0 (44.0)[4] Não suportado Não suportado ?
Feature Android Chrome for Android Edge Firefox Mobile (Gecko) IE Mobile Opera Mobile Safari Mobile
Basic support ? ? (Yes) ? ? ? ?
On disabled form elements ? ? Não suportado ? ? ? ?

[1] Implemented in bug 236215.

[2] Implemented in bug 432698.

[3] Safari 7 fires the event in many situations where it's not allowed to, making the whole event useless. See bug 470258 for the description of the bug (it existed in old Chrome versions as well). Safari 8 has correct behavior

[4] Implemented in bug 218093.

See also

Etiquetas do documento e colaboradores

 Colaboradores desta página: jppaschoal
 Última atualização por: jppaschoal,