Javascript - efficiently insert multiple HTML elements

问题

I'd like to create a select element with a list of a user's Facebook friends (obtained as a JSON object). I hardcode <select id="friends"></select> into my HTML, then use the following Javascript code to parse the JSON and insert each friend as an option of the select element:

var msgContainer = document.createDocumentFragment();
for (var i = 0; i < response.data.length; i++) { 
    msgContainer.appendChild(document.createTextNode('<option value="'+response.data[i].id+'">'+response.data[i].name+'</option>'));    
}
document.getElementById("friends").appendChild(msgContainer);

This almost works, except that it inserts < and > instead of < and >. How can I fix it, and is there a more efficient way to insert multiple HTML elements using pure Javascript (not JQuery)?

回答1:

Not sure why you're creating a text node, but it would seem that you want to create option elements, so you could use the Option constructor instead.

var msgContainer = document.createDocumentFragment();

for (var i = 0; i < response.data.length; i++) { 
    msgContainer.appendChild(new Option(response.data[i].name, response.data[i].id));
}
document.getElementById("friends").appendChild(msgContainer);

Or you can use the generic document.createElement().

var msgContainer = document.createDocumentFragment();

for (var i = 0; i < response.data.length; i++) {
    var option = msgContainer.appendChild(document.createElement("option"));
    option.text = response.data[i].name;
    option.value = response.data[i].id;
}
document.getElementById("friends").appendChild(msgContainer);

It's nice to have a helper function for creating elements and setting properties at the same time.

Here's a simple example of one:

function create(name, props) {
    var el = document.createElement(name);
    for (var p in props)
        el[p] = props[p];
    return el;
}

It can be expanded to cover some specific needs, but this will work for most cases.

You'd use it like this:

var msgContainer = document.createDocumentFragment();

for (var i = 0; i < response.data.length; i++) {
    msgContainer.appendChild(create("option", {
        text: response.data[i].name,
        value: response.data[i].id
    }));
}
document.getElementById("friends").appendChild(msgContainer);

回答2:

Try this in your for loop instead:

var o = document.createEleent('option');
o.setAttribute('value', response.data[i].id);
o.appendChild(document.createTextNode(response.data[i].name));
msgContainer.appendChild(o);

来源：https://stackoverflow.com/questions/17264182/javascript-efficiently-insert-multiple-html-elements

标签

javascript

html

getelementbyid

appendchild