Get Elements | Table O Contents

Place the introducing line of text ie.) the ‘tagline’ here …

Note. The Flammarion Logo Badge in the page header above is an .svg image file set to the dimensions of 5% width, auto height, and zoom. Go ahead and test the zoom-out feature by hovering over the badge to engage the expansion of the image.

By Class Name

Hint. Place the intro paragraph ie.) the ‘hypothesis’ here …


function getclass (x, y){
  let classes = document.body.getElementsByClassName(y);
  document.body.replaceChild(classes[x, y);
return classes.y
}
getclass("green-groove", "red-groove");

Note. In the above getclass function …

Please remember the first argument of the function takes the parameter x.

The parameter x represents the new or replacing value.

Whereas, the parameter y represents the old or the value being replaced by x.

After traversing the DOM and capturing all of the old y class names, the function then replaces all of the old y class names with new x class name, and then returns the set of classes still of the old y class name of which there should now be none.

Further, the type of the variables x and y, as well as the getclass function will be instantiated and inferred at the time of function execution.

Therefore, there is no need to declare each variable individually, nor is there a need to assign a value to the variables.

The underlying Javascript engine will infer by the structure of the function, and by the type of parameters passed as arguments.

By Tag Name

More to come …


function getpara (x, y, z){
  let paragraphs = document.body.getElementsByTagName(x);
  document.body.insertBefore(paragraphs[z], paragraphs[y]);
return paragraphs[0];
}
getpara("p", 2, 0);

Note. In the above getpara function …

The paragraph[0], commonly known as the index paragraph aka the first paragraph …

After traversing the DOM and capturing all of the x tag names of “p”, the function then inserts before the y paragraph[2] …

As a result of the function, in this case …

Therefore, the program should return the value of the the old second paragraph[1] now become the index paragraph[0].

An exercise designed to capture the first anchor link of an html page through the Javascript method getElementsByTagName() using the Javascript console of the Chrome browser and the Chrome Developer Toolset, or CDT.

This exercise has successfully yielded the following (.png) and (.log) files, as follows:

Get First Link Screen Snap


function gethref(x){
  // Declare function variables `timein`, `timeout`, and `duration` w scope `let` to check the function's speed of execution
  let timein = new Number();
  let timeout = new Number();
  let duration = new Number();
  // Assign a value to the function variable `timein`
  timein = window.console.time("checkbodytime");
  // Declare function variable `link` w scope `let` 
  let link;
  // Assign a value to the function variable `link`
  link = document.body.getElementsByTagName(x)[0];
  duration = timeout - timein;
  window.console.log(`The function took ${timeout} less ${timein} equals ${duration} ms to find the first 'href' of the '${x}' links. The first 'href' is ${link.href} and the result in milliseconds of the duration of 'checkbodytime' is displayed below along with the entire body of the returned link. Notice how the Brackets browser auto-inserts an 'Id' for the subject link if an 'Id' for the link has not yet been assigned by the programmer.`);
  // Assign a value to the function variable `timeout` prior to the return statement
  timeout = window.console.timeEnd("checkbodytime");
  return link;
}
// Call the function passing in a parameter to feed the argument
gethref("a");

Note. In the above gethref function …

Other Methods


// document.body.appendChild();

And,


// document.body.insertBefore();

Last Subtitle

More to come …


Note. The above synopsis was derived from an article written by Blank Author [1].

  1. A Narrative of Psychology by Blank Author, Jan #1999

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