为什么 JavaScript 没有进入 For...in 循环
出于某种原因，当我逐行执行时，下面的 for...in 循环不会执行。看起来它读取 Object 和 'let outerLoopProp' 语句，然后跳过整个循环体。
循环位于表单提交事件中。
我已将对象记录到控制台，并在代码到达 for..in 循环时用属性填充它。
form1.addEventListener("submit", (e) => {
e.preventDefault();
let forValidationCheck = {};
let allNames = ["Tarp 1", "Tarp 2", "Tarp 3"];
for(let r = 0; r < allNames.length; r++) {
let currentChosen = allNames[r].toLowerCase();
let optionsForCheck = document.getElementById(`selection${r+1}`);
let selectedArrayForCheck = [];
for(z=0; z < optionsForCheck.options.length; z++) {
if(optionsForCheck.options[z].selected === true) {
selectedArrayForCheck.push(optionsForCheck.options[z].value.toLowerCase());
}
}
Object.defineProperty(forValidationCheck, currentChosen, {
value: selectedArrayForCheck
})
}
for(let layerOuterLoop in forValidationCheck) {
//Code within for..in loop
}
});
<form id="form1">
<select name="selection1" id="selection1">
<option value="Tarp 1">Tarp 1</option>
<option value="Tarp 2">Tarp 2</option>
</select>
<select name="selection2" id="selection2" >
<option value="Tarp 2">Tarp 2</option>
<option value="Tarp 3">Tarp 3</option>
</select>
<select name="selection3" id="selection3">
<option value="Tarp 1">Tarp 1</option>
<option value="Tarp 3">Tarp 3</option>
</select>
<button type="submit">submit</button>
</form>
翻过高山走不出你2回答
-
波斯汪
解决方法：在使用Object.defineProperty()时，需要为方法的第三个参数设置enumerable:true。见下文。感谢大家的帮助！form1.addEventListener("submit", (e) => { e.preventDefault(); let forValidationCheck = {}; let allNames = ["Tarp 1", "Tarp 2", "Tarp 3"]; for(let r = 0; r < allNames.length; r++) { let currentChosen = allNames[r].toLowerCase(); let optionsForCheck = document.getElementById(`selection${r+1}`); let selectedArrayForCheck = []; for(z=0; z < optionsForCheck.options.length; z++) { if(optionsForCheck.options[z].selected === true) { selectedArrayForCheck.push(optionsForCheck.options[z].value.toLowerCase()); } } Object.defineProperty(forValidationCheck, currentChosen, { value: selectedArrayForCheck, enumerable: true }) } for(let layerOuterLoop in forValidationCheck) { //Code within for..in loop }});<html><head></head><body><form id="form1"> <select name="selection1" id="selection1"> <option value="Tarp 1">Tarp 1</option> <option value="Tarp 2">Tarp 2</option> </select> <select name="selection2" id="selection2"> <option value="Tarp 2">Tarp 2</option> <option value="Tarp 3">Tarp 3</option> </select> <select name="selection3" id="selection3"> <option value="Tarp 1">Tarp 1</option> <option value="Tarp 3">Tarp 3</option> </select></form></body></html> -
LEATH
做同样的事情更简单：const myForm = document.getElementById('form1') , allNames ={ 'Tarp 1': myForm.selection1 , 'Tarp 2': myForm.selection2 , 'Tarp 3': myForm.selection3 }myForm.onsubmit=e=> { e.preventDefault() let forValidationCheck = {} for (let aN in allNames) { forValidationCheck[aN.toLowerCase()] = allNames[aN].value //forValidationCheck[aN.toLowerCase()] = [allNames[aN].value] //if prefered } for (let layerOuterLoop in forValidationCheck) { console.log(layerOuterLoop, ' => ',forValidationCheck[layerOuterLoop] ) } }/* -- in case of selects are multiple : -... for (let aN in allNames) { forValidationCheck[aN.toLowerCase()] = [...allNames[aN].options] .filter(option=>option.selected) .map(option=>option.value) }*/<form id="form1"> <select name="selection1"> <option value="Tarp 1">Tarp 1</option> <option value="Tarp 2">Tarp 2</option> </select> <select name="selection2"> <option value="Tarp 2">Tarp 2</option> <option value="Tarp 3">Tarp 3</option> </select> <select name="selection3"> <option value="Tarp 1">Tarp 1</option> <option value="Tarp 3">Tarp 3</option> </select> <button type="submit">submit</button></form>
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相关分类
JavaScript