Question

我正在搜索以下事件，我需要在注册屏幕的文本框中输入的字符数自动显示在JavaScript或jQuery的同一文本框旁边。

这是初学者的问题，提前谢谢。

Answer 1

收听akeys.length事件，然后检查文本框值的长度。

var first = ["shoop", "doop", "woop", "loop"]
var second = ["hamp","damp", "samp", "wamp"]

console.log("recognized")

var returned = isEqual(first,second);

console.log(returned)

function  isEqual(a, b) {
  const aKeys = Object.getOwnPropertyNames(a)
  const bKeys = Object.getOwnPropertyNames(b)
  if (aKeys.length !== bKeys.length) {
    return aKeys.every((key, index) => {
      key === bKeys[index]
    })
  }
  else{
   return true
  }
}

import Cocoa


func findAll<T: Equatable, C: Collection>(items: C, itemToFind: T) -> [C.Index]?  where C.Iterator.Element == T  {

  guard items.contains(itemToFind) else {
    return nil
  }

  var result = Array<C.Index>()
  var index = items.startIndex
  for item in items {
    if item == itemToFind {
      result.append(index)
    }
    index = items.index(after: index)   //    index = index.successor()
  }
  return result

  //  Another approach:
  //  return items.indices.filter { items[$0] == itemToFind }

}

print("\nList the Indicies within 'items' of where 'itemToFind' was found")


let Indexes1 = findAll(items: [5, 3, 7, 3, 9], itemToFind: 3)                    // result: [1, 3]
print(Indexes1!)
let Indexes2 = findAll(items: ["c", "a", "b", "c", "a"], itemToFind: "c")        // result: [0, 3]
print(Indexes2!)



func offsetValue(input: String.CharacterView, position: String.CharacterView.Index) -> Int {
  let offset = input.distance(from: input.startIndex, to: position)
  return offset
}

var i = 0
let stringChars = "Hello, playground!".characters
let stringIndexes = findAll(items: stringChars, itemToFind: Character("l"))       // result: [2, 3, 8]
print("[", terminator: "")
for  stringIndex in stringIndexes! {
  let stringIndexInt = offsetValue(input:stringChars, position: stringIndex)
  print("\(stringIndexInt)", terminator: "")
    i += 1
  if i < (stringIndexes?.count)! {
    print(", ", terminator: "")
  }
}
print("]")

Answer 2

恕我直言，按键应该是寻找字符数的理想事件。

$('#input').on('keypress', function(e) {
    var count = $(this).val().length;
    $('#span').text(count);
}

Keypress vs. Keyup 如果我按住任意一个字符键几秒钟，它就会在输入框中输入几个字符，而keyup事件会给你一个1的计数，因为键只被提升一次。但是，按键会输入确切的字符数。

如何计算在文本框中输入的字符数并在其旁边自动显示？

2 个答案: