Wsrtjtyk

I want to pass the parameter value in style for calculate my width. my code is

function getValue(value) {

  if (value === 12) {

    return {

      width: '( 20 - value )%',

    };

  }

  return false;

}

but the width does not working. I am new to react. please help.

You can't calculate if it's a string. Quote marks ('') make it a string. Also, % is a remainder operator. It gets the remainder of two numbers. It's similar to division. You can read more about the remainder operator on MDN
I don't understand what this has to do with react, this is more just vanilla javascript.

I think what you may want is

function getValue(value) {

  if (value !== 12) { return false; }

  return {

    width: (20 - value)/100,

  };

}

You could also do the following since it only returns if the value if 12

var getValue = value => value === 12 ? { width: 0.08 } : false

This solution uses arrow functions, auto return, and ternary operators. You can read about them on mdn

You need something like below. You are checking a constant value, so no need to do the arithmetic, just return 8. You can simplify the function as like below

function getValue(value) {

  // return object for style or undefined for no styling

  return value === 12 ? {'width': '8% !important' } : undefined;

}

If you were to keep the arithmetic because you wanted to just always do a calculation (for instance). Then a nicer way to write out the function would be like this.

function getValue(value) {

  return { 'width': `${20 - value}% !important` };

}

Try this

width: (20 - value) + ‘%’