This javascript code can be used in a custom field as an example of making fields (in this case "Featured Start" and "Featured End") visible conditionally based on the value of another field.
Read the full explanation at LearndotCMS.com.
// Prevent namespace collisions with Dojo, etc
var j = jQuery.noConflict();
// Function to show/hide fields
function toggleFields(val) {
if(val == '0') {
j("${esc.dollar}{esc.h}featuredStart_tag,${esc.dollar}{esc.h}featuredEnd_tag").parent().hide();
} else {
j("${esc.dollar}{esc.h}featuredStart_tag,${esc.dollar}{esc.h}featuredEnd_tag").parent().show();
}
}
j(document).ready(function() {
// Hide our custom field's label
j('${esc.dollar}{esc.h}conditionalFields_tag').parent().hide();
// Check the field state on load and show/hide our conditional fields as appropriate
var startingVal = j("input:radio[name=bool1]").val();
toggleFields(startingVal);
// Add click handler to show/hide fields on controlling radio button
j("input:radio[name=bool1]").click(function() {
toggleFields(j(this).val());
});
});