[英]setAttribute with javascript inside a for evaluation
我正在嘗試為元素設置屬性。
從類(活動)中提取元素並為其分配變量。 相同的元素從另一個類(topArrow)中提取,並分配了一個變量。
比較兩個變量以運行if語句時,求值結果不相同... ???
console.log看看發生了什么,我得到了:
HTMLCollection[img.active images/a.../top.png]
HTMLCollection[]
在不具有topArrow類的元素上,我得到的是:
HTMLCollection[img.active images/a...left.png]
HTMLCollection[img.topArrow images/a.../top.png]
var arrow = 0;
var topArrow = document.getElementsByClassName("topArrow");
var menuText = document.getElementsByClassName("menuText");
var rightArrow = document.getElementsByClassName("rightArrow");
var bottomArrow = document.getElementsByClassName("bottomArrow");
var leftArrow = document.getElementsByClassName("leftArrow");
//assign navButtons to var buttons (creates array)
var buttons = document.getElementsByClassName("navButton");
//for each instance of buttons, assign class "active" onmouseover
for(var i = 0; i < buttons.length; ++i){
buttons[i].onmouseover = function() {
this.className = "active";
var arrow = document.getElementsByClassName("active");
console.log(arrow);
console.log(topArrow);
changeImages();
}
}
//for each instance of buttons, remove class "active" onmouseout
for(var i = 0; i < buttons.length; ++i){
buttons[i].onmouseout = function () {
this.className = "";
};
}
function changeImages(){
if ( arrow == topArrow ) {
this.setAttribute("src", "images/arrows/top_o.png");
console.log("arrow should change");
} else {
console.log("arrow should not change");
}
}
您正在重新定義函數作用域中的arrow
,這使全局定義蒙上了陰影。
var arrow = 0;//global
var arrow = document.getElementsByClassName("active");// overshadowing assignment
即使您修復的是刪除var
,因此-
arrow = document.getElementsByClassName("active");// var removed
使用document.getElementByClassName
,即使存在一個匹配項,也將獲得HTMLCollection
,而不是該元素。 使用==
匹配數組不會按照您想要的方式運行。
要解決該問題-
if(arrow[0] == toparrow[0])//assuming you have only one element with class 'active' and 'toparrow' in dom
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