Get the value of input text when enter key pressed

Try this:

<input type="text" placeholder="some text" class="search" onkeydown="search(this)"/>  
<input type="text" placeholder="some text" class="search" onkeydown="search(this)"/>

JS Code

function search(ele) {
    if(event.key === 'Enter') {
        alert(ele.value);        
    }
}

DEMO Link

$("input").on("keydown",function search(e) {
    if(e.keyCode == 13) {
        alert($(this).val());
    }
});

jsFiddle example : http://jsfiddle.net/NH8K2/1/

Just using the event object

function search(e) {
    e = e || window.event;
    if(e.keyCode == 13) {
        var elem = e.srcElement || e.target;
        alert(elem.value);
    }
}

You should not place Javascript code in your HTML, since you're giving those input a class ("search"), there is no reason to do this. A better solution would be to do something like this :

$( '.search' ).on( 'keydown', function ( evt ) {
    if( evt.keyCode == 13 )
        search( $( this ).val() ); 
} ); 

Listen the change event.

document.querySelector("input")
  .addEventListener('change', (e) => {
    console.log(e.currentTarget.value);
 });