使用數組創建狀態下拉菜單

Question

如何使用陣列創建美國所有州的選擇下拉菜單？ 我在.js文件中寫了以下內容：

    var usStates = [
    { name: 'ALABAMA', abbreviation: 'AL'},
    { name: 'ALASKA', abbreviation: 'AK'},
    { name: 'AMERICAN SAMOA', abbreviation: 'AS'},
    { name: 'ARIZONA', abbreviation: 'AZ'},
    { name: 'ARKANSAS', abbreviation: 'AR'},
    { name: 'CALIFORNIA', abbreviation: 'CA'},
    { name: 'COLORADO', abbreviation: 'CO'},
    { name: 'CONNECTICUT', abbreviation: 'CT'},
    { name: 'DELAWARE', abbreviation: 'DE'},
    { name: 'DISTRICT OF COLUMBIA', abbreviation: 'DC'},
    { name: 'FEDERATED STATES OF MICRONESIA', abbreviation: 'FM'},
    { name: 'FLORIDA', abbreviation: 'FL'},
    { name: 'GEORGIA', abbreviation: 'GA'},
    { name: 'GUAM', abbreviation: 'GU'},
    { name: 'HAWAII', abbreviation: 'HI'},
    { name: 'IDAHO', abbreviation: 'ID'},
    { name: 'ILLINOIS', abbreviation: 'IL'},
    { name: 'INDIANA', abbreviation: 'IN'},
    { name: 'IOWA', abbreviation: 'IA'},
    { name: 'KANSAS', abbreviation: 'KS'},
    { name: 'KENTUCKY', abbreviation: 'KY'},
    { name: 'LOUISIANA', abbreviation: 'LA'},
    { name: 'MAINE', abbreviation: 'ME'},
    { name: 'MARSHALL ISLANDS', abbreviation: 'MH'},
    { name: 'MARYLAND', abbreviation: 'MD'},
    { name: 'MASSACHUSETTS', abbreviation: 'MA'},
    { name: 'MICHIGAN', abbreviation: 'MI'},
    { name: 'MINNESOTA', abbreviation: 'MN'},
    { name: 'MISSISSIPPI', abbreviation: 'MS'},
    { name: 'MISSOURI', abbreviation: 'MO'},
    { name: 'MONTANA', abbreviation: 'MT'},
    { name: 'NEBRASKA', abbreviation: 'NE'},
    { name: 'NEVADA', abbreviation: 'NV'},
    { name: 'NEW HAMPSHIRE', abbreviation: 'NH'},
    { name: 'NEW JERSEY', abbreviation: 'NJ'},
    { name: 'NEW MEXICO', abbreviation: 'NM'},
    { name: 'NEW YORK', abbreviation: 'NY'},
    { name: 'NORTH CAROLINA', abbreviation: 'NC'},
    { name: 'NORTH DAKOTA', abbreviation: 'ND'},
    { name: 'NORTHERN MARIANA ISLANDS', abbreviation: 'MP'},
    { name: 'OHIO', abbreviation: 'OH'},
    { name: 'OKLAHOMA', abbreviation: 'OK'},
    { name: 'OREGON', abbreviation: 'OR'},
    { name: 'PALAU', abbreviation: 'PW'},
    { name: 'PENNSYLVANIA', abbreviation: 'PA'},
    { name: 'PUERTO RICO', abbreviation: 'PR'},
    { name: 'RHODE ISLAND', abbreviation: 'RI'},
    { name: 'SOUTH CAROLINA', abbreviation: 'SC'},
    { name: 'SOUTH DAKOTA', abbreviation: 'SD'},
    { name: 'TENNESSEE', abbreviation: 'TN'},
    { name: 'TEXAS', abbreviation: 'TX'},
    { name: 'UTAH', abbreviation: 'UT'},
    { name: 'VERMONT', abbreviation: 'VT'},
    { name: 'VIRGIN ISLANDS', abbreviation: 'VI'},
    { name: 'VIRGINIA', abbreviation: 'VA'},
    { name: 'WASHINGTON', abbreviation: 'WA'},
    { name: 'WEST VIRGINIA', abbreviation: 'WV'},
    { name: 'WISCONSIN', abbreviation: 'WI'},
    { name: 'WYOMING', abbreviation: 'WY' }
];

alert(usStates[1].name);
for ( var i = 0; i >= 50; i--) {
    var opt1 = usStates[i].abbreviation;
    var opt2 = usStates[i].name;
    var select = document.getElementById("state");
    var option = document.createElement("OPTION");
    option.text = opt1;
    option.value = opt2;
    select.options.add(option);
}

然后在我的html文件中：

    State: <select id="state"></select> 

但是，下拉菜單為空，無法正常工作。 有任何想法嗎？

Answer 1

根據您的代碼，您可以執行以下操作：

var stateSelect = document.getElementById('state');

for(var i = 0; i < usStates.length; i++) {
    var option = document.createElement("option");
    option.text = usStates[i].name;
    option.value = usStates[i].abbreviation;
    stateSelect.add(option);
}

Answer 2

你的問題是你的var i循環是錯誤的。 你必須執行循環，而我小於50並且不大於......這是你的問題！

for ( var i = 0; i >= 50; i--)

你永遠不會以這種方式進入循環。

在你的html某處，你有這個：

<select id="state" name="states"></select>

然后在您的JavaScript中，您可以執行以下操作：

//your array of states objects declared before, array name is 'states'

for(var i = 0;i<states.length;i++){
    var option = document.createElement("option");
    option.text = states[i].name+' ['+states[i].abbreviation+']';
    option.value = i;
    var select = document.getElementById("state");
    select.appendChild(option);
}

檢查一下，這很好用： http ： //jsfiddle.net/bx8aa0et/2/

希望能幫助到你！