Replace values from a string if they are present in an array of variables-CodePudding

Having the following array of objects:

const variables = [
  { name: '%NAME%', value: 'joe' },
  { name: '%EMAIL%', value: '%NAME%@mail.com' },
  { name: '%HOBBY%', value: 'tennis' }
];

And the input string:

const inputString = `Hi, my name is %NAME%', I like %HOBBY%, you can contact me at %EMAIL%`;

The function should take as arguments variables and inputString and return the following sting:

'Hi, my name is joe, I like tennis, you can contact me at [email protected]'

Here is the function so far:

function doMagic(variables, inputString) {
  let output = inputString;
  for (let i = 0; i < variables.length; i  ) {
     output = inputString.replace(variables[i].name, variables[i].value);
  }
  return output;
}

Unfortunatelly, this only finds one occurrence, in case there are more, and it doesn't go into nested variables, like %EMAIL%.

Any ideas to improve?

CodePudding user response：

We can do a regex replacement with the help of a callback function:

var variables = [
                   {name: '%NAME%', value: 'joe'},
                   {name: '%EMAIL%', value: '[email protected]'},
                   {name: '%HOBBY%', value: 'tennis'}
                  ];
var regex = new RegExp("("   variables.map(x => x.name).join("|")   ")", "g");
var inputString = "Hi, my name is %NAME%, I like %HOBBY%, you can contact me at %EMAIL%";
var output = inputString.replace(regex, (m) => {
    return variables.filter(x => x.name == m)[0].value;
});
console.log(output);

The strategy here is to first build a regex alternation of names from the map. We do a global regex search for these names in the input string. For each match, the callback function replaces the name with the value from the map.

CodePudding user response：

You could do a recursive call until there are no variables left in the string

const variables = [
  { name: '%NAME%', value: 'joe' },
  { name: '%EMAIL%', value: '%NAME%@mail.com' },
  { name: '%HOBBY%', value: 'tennis' },
];

const inputString = `Hi, my name is %NAME%', I like %HOBBY%, you can contact me at %EMAIL%`;

function doMagic(variables, inputString) {
  let output = inputString;
  for (let i = 0; i < variables.length; i  ) {
    output = output.replace(variables[i].name, variables[i].value);
  }
  for (let i = 0; i < variables.length; i  ) {
    if (output.includes(variables[i].name)) {
      output = doMagic(variables, output);
    }
  }
  return output;
}

console.log(doMagic(variables, inputString));

CodePudding user response：

Issues.

You have not updated inputString after string replace.

I have made use of below logic.

Loop through variables first.
Replace the values if any of the value consist of node from variable array itself (in our case replace %NAME%@mail.com as [email protected])
Use this replaced array to perform replacement of string values from inputString.
Use replaceAll instead of replace to handle multiple ovvurance of same variable.

const variables = [
  { name: '%NAME%', value: 'joe' },
  { name: '%EMAIL%', value: '%NAME%@mail.com' },
  { name: '%HOBBY%', value: 'tennis' }
];
const inputString = `Hi, my name is %NAME%', I like %HOBBY%, you can contact me at %EMAIL%`;
function doMagic(variables, inputString) {
  let output = inputString;
  // First replace variables
  for (let i = 0; i < variables.length; i  ) {
    const node = variables.find(item => item.value.includes(variables[i].name));
    if (node) {
      node.value = node.value.replaceAll(variables[i].name, variables[i].value);
    }
  }
  for (let i = 0; i < variables.length; i  ) {
    output = output.replaceAll(variables[i].name, variables[i].value);
  }
  return output;
}
console.log(doMagic(variables, inputString))

CodePudding user response：

You can use replaceAll method to replace all the occurrence and loop twice.

function doMagic(variables, inputString) {
  let output = inputString;
  for (let i = 0; i < variables.length; i  ) {
     output = output.replaceAll(variables[i].name, variables[i].value);
  }
  for (let i = 0; i < variables.length; i  ) {
     output = output.replaceAll(variables[i].name, variables[i].value);
  }
  return output;
}

CodePudding user response：

My solution with use "reduce"

const variables = [
  { name: "%NAME%", value: "joe" },
  { name: "%EMAIL%", value: "%NAME%@mail.com" },
  { name: "%HOBBY%", value: "tennis" }
];
const inputString =
  "Hi, my name is %NAME%, I like %HOBBY%, you can contact me at %EMAIL%";

function doMagic(string, variables) {
  const replaceVar = (s, v) =>
    v.reduce((prev = "", { name, value }) => prev.replace(name, value), s);
  const fixedVariables = variables.map((v) => ({
    ...v,
    value: replaceVar(v.value, variables)
  }));

  return replaceVar(string, fixedVariables);
}

console.log(doMagic(inputString, variables));

Also if you want, you can modify my code to prototype, like this:

const inputString =
  "Hi, my name is %NAME%, I like %HOBBY%, you can contact me at %EMAIL%";

String.prototype.doMagic = function (variables) {
  const replaceVar = (s, v) =>
    v.reduce((prev = "", { name, value }) => prev.replace(name, value), s);
  const fixedVariables = variables.map(({ value, ...rest }) => ({
    ...rest,
    value: replaceVar(value, variables)
  }));

  return replaceVar(this, fixedVariables);
};


console.log(
  inputString.doMagic([
    { name: "%NAME%", value: "joe" },
    { name: "%EMAIL%", value: "%NAME%@mail.com" },
    { name: "%HOBBY%", value: "tennis" }
  ])
)