如何从字符串中获取最小/最大int值？

Question

I have a many elements in page whis id = "item(\\d{1,})" . How to quickly get element id with a min value and max value of (\\d{1,}) regexp ?

Answer 1

Use this to get list of your IDs:

$j("[id^=item]").map(function(){ return Number(this.id.substr(4)); });

I don't think jQuery has any tools to quickly get min/max value, but it is pretty trivial to write yourself.

As per Vivin's request providing the trivial part:

var arr = $j("[id^=item]").map(function(){ return Number(this.id.substr(4)); }).sort();
var min = arr[0];
var max = arr[arr.length-1];

Answer 2

You can also use querySelectorAll if the browser supports it; all browsers should select it. IE has supported it since 8.

var elements = document.querySelectorAll("[id^=item]");
var max = null;
var min = null;
for(var i = 0; i < elements.length; i++) {

   var number = elements[i].id.replace(/item/, "");

   if(max == null) {
      max = number;
      min = number;
   }

   else {
      max = (number > max) ? number : max;
      min = (number < min) ? number : min;
   }
}

If the browser doesn't support it, you would have to do something like this:

//assuming that you're looking for div; just replace it with the actual element 
//you're looking for
var elements = document.getElementsByTagName("<div">); 

var max = null;
var min = null;
for(var i = 0; i < elements.length; i++) {
    if(/item\d+/.test(elements[i].id)) {
       var number = elements[i].id.replace(/item/, "");

       if(max == null) {
          max = number;
          min = number;
       }

       else {
          max = (number > max) ? number : max;
          min = (number < min) ? number : min;
       }
    }
}

Or if you're using jQuery:

var max = null;
var min = null;
jQuery("[id^=item]").each(function() {
    var number = this.id.replace(/item/, "");

    if(max == null) {
       max = number;
       min = number;
    }

    else {
       max = (number > max) ? number : max;
       min = (number < min) ? number : min;
    }
});