Javascript 在循环中将参数传递给 addeventListener 函数

Question

此代码将把循环创建的最后一个值传递给 eventListener 函数，我需要附加创建 eventListener 时的值。

window.onload = function() {

var el = document.getElementsByClassName('modify');

for (var i = 0; i < el.length; i++) {

     var getId=el[i].id.split("_");

     document.getElementById("modify_y_"+getId[2]).addEventListener('mouseover', function() {
     document.getElementById("modify_x_"+getId[2]).style.borderBottom = '#e6665 solid 3px';
    }, false); 

}
}

Answer 1

您可以使用现代浏览器中所有函数中都存在的bind原型(prototype)

window.onload = function() {

var el = document.getElementsByClassName('modify');

for (var i = 0; i < el.length; i++) {

     var getId=el[i].id.split("_");

     document.getElementById("modify_y_"+getId[2]).addEventListener('mouseover', function(theid) {
       document.getElementById("modify_x_"+getId[2]).style.borderBottom = '#e6665 solid 3px';
    }.bind(null,getId[2]), false); 

}
}

如果您需要支持未内置 bind 的旧版浏览器，您可以使用此 poly-fill taken from MDN您还可以在其中找到有关绑定(bind)原型(prototype)函数的文档

if (!Function.prototype.bind) {
  Function.prototype.bind = function (oThis) {
    if (typeof this !== "function") {
      // closest thing possible to the ECMAScript 5 internal IsCallable function
      throw new TypeError("Function.prototype.bind - what is trying to be bound is not callable");
    }

    var aArgs = Array.prototype.slice.call(arguments, 1), 
        fToBind = this, 
        fNOP = function () {},
        fBound = function () {
          return fToBind.apply(this instanceof fNOP && oThis
                                 ? this
                                 : oThis,
                               aArgs.concat(Array.prototype.slice.call(arguments)));
        };

    fNOP.prototype = this.prototype;
    fBound.prototype = new fNOP();

    return fBound;
  };
}