javascript - 如何知道输入中输入的最后一个字符 - Javascript

Question

假设我们有以下输入:

<input id="myInput" type='text' onkeyup="validate(this.value)" />

function validate(character) {
    console.log(character)
}

问题是我只能得到输入的总体值。例如，如果我写 2，它会返回 2，但如果我写 7，它会返回 27，而它应该只返回 7。

Answer 1

只需检索 KeyboardEvent 属性 key来自这样的“keyup”事件:

//assign the input element to a variable
let input = document.querySelector("#myInput"); 

//add a keyup listener to the input that will run the function passing the event to the function as an argument
input.addEventListener("keyup", function(e) {
    console.log(e.key);
});

<input id="myInput" type='text'/>

JSFiddle 包含上述代码: https://jsfiddle.net/AndrewL64/n18wqzjm/4/

---

但是等等，如果我希望某些键运行其他内容(例如运行不同的 console.log)怎么办？

好吧，您只需添加一个条件语句来检查键属性值并将其与单个键进行比较，如下所示:

let input = document.querySelector("#myInput");

input.addEventListener("keyup", function(e) {
	if (e.key === "Delete") {
    //if the DELETE key is pressed, don't run the default console.log but do something else
    console.log("You are trying to add delete key as a character: " + e.key);
  } else if (e.key === "Escape") {
    //if the ESCAPE key is pressed, don't run the default console.log but do something else
  	console.log("You are trying to add escape key as a character: " + e.key);
  } else {
    //run the default console.log
  	console.log(e.key);
  }
});

<input id="myInput" type='text'/>