Given a String that represents a math operation , i want to extract the operations it contains , for ex : 5 4-3 will return two arrays : Operations = [ ,-] and the operands will be [5,4,3]

// grab the input and so stuff when user finishes typing

const selectElement = document.querySelector('.formule');
selectElement.addEventListener('change', (event) => {
  const result = document.querySelector('.result');
  segmentFormule(event.target.value);
});


const segmentFormule = function (value){
// first separate operands from operations
    let myOperands = [];
    const formule = new String(value);
    
    // here i extracted the operands into an array, but i couldnt figure out how to extract the operations , so i just hardcoded Addition operation for now.
    
    myOperands=formule.split(" ");
    
    let ColoredFormule = "";
    for (var i = 0 ; i < myOperands.length ; i   ) {
        ColoredFormule  = 
        '<span style="color:Red">' myOperands[i] '</span> ' '<span style="color:blue"> </span> ';
    }
    document.querySelector('.result').innerHTML = ColoredFormule;
    
    }

<label for="formuleField">Example input: 56 400 300</label>
</br>
<input type="text" class="formule" name="formuleField">
</br>
<div class="result"></div>

<iframe name="sif1" sandbox="allow-forms allow-modals allow-scripts" frameborder="0"></iframe>

I Couldnt figure out how to extract the operations from the given input, any help is appreciated.

CodePudding user response：

Use a regular expression to create two arrays using match. The first match will match against all none numbers, the second will match against all the numbers.

If you want integers in your operators array map over the array passing in Number for the callback.

const str = '5.14   4 - 36';
const operations = str.match(/[^\d \.]/g);
const operands = str.match(/\d \.?\d*/g).map(Number);
console.log(operations, operands)

<iframe name="sif2" sandbox="allow-forms allow-modals allow-scripts" frameborder="0"></iframe>

CodePudding user response：

You can use regex with string.match()
(notice the digits are strings, if you need numbers, you have to convert)

let value = '56.2 400-300/200*.23'

const operatorsRegex = /[ \-/*]/g

let operators = value.match(operatorsRegex)

console.log(operators) // [' ','-','/','*']

const digitsRegex = /(\d \.?\d*)|(\.?\d )/g

let digits = value.match(digitsRegex)
console.log(digits) // ["56.2", "400", "300", "200", ".23"]

<iframe name="sif3" sandbox="allow-forms allow-modals allow-scripts" frameborder="0"></iframe>