等效于angularjs ng-if的JavaScript

Question

If I want to remove/add element on DOM I just use ng-if and the code under it does not compile into to DOM, can I do the same using pure js? I don't want the HTML code inside my js code.

Hiding it using CSS:

<div id = "infoPage" style="display: none;">

Will still insert the element to the DOM.

EDIT

The condition for showing or not is based on a flag like:

var show = false; //or true

Answer 1

You can try something like this:

Idea:

• Create an object that holds reference of currentElement and its parent ( so you know where to add ).
• Create a clone of current element as you want to add same element after its removed.
• Create a property using Object.defineProperty . This way you can have your own setter and you can observe changes over it.
• To toggle element, check
  • If value is true, you have to add element. But check if same element is already available or not to avoid duplication.
  • If false, remove element.

 var CustomNGIf = function(element, callback, propertyName) { var _value = null; // Create copies of elements do that you can store/use it in future this.parent = element.parentNode; this.element = element; this.clone = null; // Create a property that is supposed to be watched Object.defineProperty(this, propertyName, { get: function() { return _value; }, set: function(value) { // If same value is passed, do nothing. if (_value === value) return; _value = !!value; this.handleChange(_value); } }); this.handleChange = function(value) { this.clone = this.element.cloneNode(true); if (_value) { var index = Array.from(this.parent.children).indexOf(this.element); // Check if element is already existing or not. // This can happen if some code breaks before deleting node. if (index >= 0) return; this.element = this.clone.cloneNode(true); this.parent.appendChild(this.element); } else { this.element.remove(); } // For any special handling callback && callback(); } } var div = document.getElementById('infoPage'); const propName = 'value'; var obj = new CustomNGIf(div, function() { console.log("change") }, propName); var count = 0; var interval = setInterval(function() { obj[propName] = count++ % 2; if (count >= 10) { window.clearInterval(interval); } }, 2000) 

 <div class='content'> <div id="infoPage"> test </div> </div> 

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