zulip/static/templates/settings/custom_user_profile_field.hbs

<div class="custom_user_field" name="{{ field.name }}" data-field-id="{{ field.id }}">
    <label class="inline-block" for="{{ field.name }}" class="title">{{ field.name }}</label>
    <div class="alert-notification custom-field-status"></div>
    <div class="field_hint">{{ field.hint }}</div>
    <div class="field">
        {{#if is_long_text_field}}
        <textarea maxlength="500" class="custom_user_field_value">{{ field_value.value }}</textarea>
        {{else if is_select_field}}
        <select class="custom_user_field_value">
            <option value=""></option>
            {{#each field_choices}}
            <option value="{{ this.value }}" {{#if this.selected}}selected{{/if}}>{{ this.text }}</option>
            {{/each}}
        </select>
        {{else if is_user_field }}
        <div class="pill-container person_picker">
            <div class="input" contenteditable="true"></div>
        </div>
        {{else if is_date_field }}
        <input class="custom_user_field_value datepicker" data-field-id="{{ field.id }}" type="text"
          value="{{ field_value.value }}" />
        <span class="remove_date"><i class="fa fa-close"></i></span>
        {{else}}
        <input class="custom_user_field_value" type="{{ field_type }}" value="{{ field_value.value }}" maxlength="50" />
        {{/if}}
    </div>
</div>