删除数字字符串的最后一个字母

Question

I'm trying to make a calculator. The code inside the Plus functions work correctly and concatenates the string. Pressing these two buttons below...

document.getElementById('Textbox').innerHTML += '5';
document.getElementById('Textbox').innerHTML += '9';

Results in the intended 59 being printed to screen.

I want to go back to 5, deleting the 9, so the Calculator's CE button. But this code below makes the number on screen 58. How do I force JS to see this as a string type?

document.getElementById('Textbox').innerHTML--;

Answer 1

For that use substring method

var a = "59";
a = a.substring(0, a.length - 1);
console.log(a);
result: 5

Answer 2

I would call split on innerHtml to cast it to an array of characters. I would then use the pop method to remove the last character. And then use join to create a string that you can assign to innerHtml.

 const textBoxElement = document.getElementById('Textbox'); // create an array of characters const innerHtml = textBoxElement.innerHTML.split(''); // remove the last character innerHtml.pop(); // create and assign a string textBoxElement.innerHtml = innerHtml.join('');