budget-calculator-1.js

// HTML Element
<budget-calculator no-headline></budget-calculator>

// Polymer template code
<template is="dom-if" if="{{showHeadline}}">
  <h1>This is my headline</h1>
</template>


// Polymer JavaScript code
properties: {
  noHeadline: {
    type: Boolean,
    value: false,
  },
  showHeadline: {
    type: Boolean,
    computed: 'computeShowHeadline(noHeadline)'
  }
},

computeShowHeadline: function(noHeadline) {
  // Return the opposite of `noHeadline`.
  // If `noHeadline` is FALSE, then `showHeadline` will be TRUE
  // If `noHeadline` is TRUE, then `showHeadline` will be FALSE
  return !noHeadline;
}