Applying replace multiple times (dynamicly with Javascript)

Question

I have the current function:

function replaceValue(v) {
  const firstRegex = new RegExp('hello', 'g');
  const secondRegex = new RegExp('bye', 'g');

  return v.replace(firstRegex, '@').replace(secondRegex, '#');
}

However, now I want to add even more regex, and I want to have a datastructure that looks like this:

const regexStorage = [{
 value: '@',
 replace: 'hello',
}, {
 value: '#',
 replace: 'bye',
}]

I can't figure out a way to use that regexStorage to dynamically add as many replaces as they exist in the array for a given value.

I've got to this:

function replaceValue(v) {
  const firstRegex = new RegExp(regexStorage[0].replace, 'g');
  const secondRegex = new RegExp(regexStorage[1].replace, 'g');

  return v.replace(firstRegex, regexStorage[0].value).replace(secondRegex, regexStorage[1].value);
}

But that's just using the storage. I wonder how I can do this dynamically.

junvar · Accepted Answer · 2019-06-13 14:14:32Z

2

In JS, you can write a one-line reduce (which was designed for this exact scenario of operating on an array but returning a single value) (mdn) loop as:

const regexStorage = [{
 value: '@',
 replace: 'hello',
}, {
 value: '#',
 replace: 'bye',
}];

let replaceValue = v => regexStorage.reduce((v, {value, replace}) => v.replace(new RegExp(replace, 'g'), value), v);

let str = 'hi hello bye bi hello';
console.log(replaceValue(str));
console.log(str);

edited Jun 13, 2019 at 14:14

answered Jun 13, 2019 at 14:03

junvar

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7 Comments

Hommer Smith Over a year ago

Would this change the original v value?

junvar Over a year ago

No. JS, like most languages including Java and C++, passes primitives by value. Updated snippet to exemplify the unchanged argument value.

Hommer Smith Over a year ago

I'm confused on why is the argument named v and also the value in the reduce function is called v.

junvar Over a year ago

You could name them different, but since they represent the same value, it makes sense to keep the same name. It's like if you had a function purchase(cost), which then called function chargeCreditCard(cost) and function calcTax(cost), all 3 functions have the same param name because it represents the same thing.

junvar Over a year ago

Alternatively, you could have different names:

let replaceValue = str => regexStorage.reduce((v, {value, replace}) => v.replace(new RegExp(replace, 'g'), value), str);

|

Andam · Accepted Answer · 2019-06-13 14:01:07Z

1

You can just loop through your regex storage

const regexStorage = [
  {
   value: '@',
   replace: 'hello',
  }, 
  {
   value: '#',
   replace: 'bye',
  }
]


function replaceValue(v) {
  for(var i = 0; i < regexStorage.length; i++){
    v = v.replace(new RegExp(regexStorage[i].replace, "g"), regexStorage[i].value);
  }
  return v;
}
var data = "hello, my name is andam. bye.";
console.log(data);
console.log(replaceValue(data));

answered Jun 13, 2019 at 14:01

Andam

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