Finding Closest Matching Value using jQuery or javascript

问题

Consider a markup such as

<select id="blah">
  <option value="3">Some text</option>
  <option value="4">Some text</option>
  <option value="8">Some text</option> // <---- target this tag based on value 7
  <option value="19">Some text</option>
</select>

Suppose I have a value with me, say 7. Is it possible to target the option tag whose value attribute is closest to 7 which, in this case, would be <option value="8">?

I'm aware of ^ which means starting with and $ which means ending with and was hoping if there is something like this to find the closest match for a given value.

回答1:

I'll go like this:

http://jsfiddle.net/GNNHy/

var $tmpOption = $('<option value="7">Some text 7</option>');
$("#blah").append($tmpOption);
var my_options = $("#blah option");
my_options.sort(function(a,b) {
    if (parseInt(a.value,10) > parseInt(b.value,10)) return 1;
    else if (parseInt(a.value,10) < parseInt(b.value,10)) return -1;
    else return 0
})

$("#blah").empty().append( my_options );

回答2:

How about a recursion? It will find the closest value:

JS-BIN Demo

function getClosest(val, ddl, increment){
  if(ddl.find('option[value="'+val+'"]').length){
      return val;
  }
  else
    try{
      if(increment)
    return getClosest(++val, ddl, increment);
      else
        return getClosest(--val, ddl, increment);
    }
  catch(err){
    return -1;
  }
}

function findClosest(val, ddl){
   var larger = getClosest(val, ddl, true);
   var smaller = getClosest(val, ddl, false);
  if(larger == smaller == -1)
    return -1;
  else if (larger == -1)
    return smaller;
  else if (smaller == -1 )
    return larger;

  if(larger - val > val - smaller)
    return smaller;
  else
    return larger
}

回答3:

Yes just substract your value (7) with the option values(use each function)...the value with the minimum positive outcome will be your targeted option. I hope you will have the desired result.

回答4:

The easiest way is perhaps the good old linear search (you can do binary, but it's more tricky than usual):

var target;
var $options;

var best=Infinity;
var bestAt;

$options.each(function(){
  var error = this.value - target;
  error = error>0 ? error : -error;
  if(error<=best){
    best=error;
    bestAt=this;
  }
})

//return $(bestAt);

回答5:

function findClosest(num){
    var select = document.getElementById('blah');
    var options = select.options;
    var dif = Infinity;
    var index;
    for(var i = 0; i < options.length; i++){
        var newdif = Math.abs(parseInt(options[i].value) - num);
        if(newdif < dif){
             dif = newdif;
             index = i;
        }
    }
    select.selectedIndex = index;
}

回答6:

If you can use jquery I would do something like

$(function () {
        // comes from somewhere
        var val = 7;

        var sortByDifference = $("#blah option").sort(function (opt1, opt2) {
            return Math.abs(parseInt($(opt1).val()) - val) - Math.abs(parseInt($(opt2).val()) - val);
        });

        alert($(sortByDifference[0]).val());
    });

In sortByDifference you have all values sorted by how close they are to your value. The routine returns the closest greater or lower and doesn't require the options to be sorted.

来源：https://stackoverflow.com/questions/14255698/finding-closest-matching-value-using-jquery-or-javascript

标签

javascript

jquery

option