Replace string with items from an object

Question

I’m trying to do the replace of a string, similar to the one in the example, in it I have wildcards ${} and within it I have those who would be the key to an object for substitution.

Given this explanation, what would be the best option to make this replacement ?

    let string = 'PP24,260:AN7'+
    'BARSET "QRCODE",1,1,11,2,1'+
    'PB "${qrcode}"'+
    'PP 270,265'+
    'PT "${cliente}"'+
    'PP 270,225'+
    'PT "${comprimento}"'+
    'PP 270,185'+
    'PT "${diametro}"'+
    'PP 270,145'+
    'PT "${espessura}"'+
    'PP 270,105'+
    'PT "${aco}"'+
    'PP 270,65'+
    'PT "${peso}"'+
    'PP 550,145'+
    'PT "${lote}"'+
    'PP 550,105'+
    'PT "${ordem}"'+
    'PP 550,65'+
    'FT "Swiss 721 BT",11'+
    'PT "${data}"'+
    'LAYOUT RUN ""'+
    'PF'+
    'PRINT KEY OFF';
    
    let obj = {
      qrcode: "asd1231",
      cliente: "1321384a684a654a564z6",
      comprimento: "1256.2",
      diametro: "13.5",
      espessura: "26.5",
      aco: "3695z",
      peso: "165.00",
      lote: "65zxc651z3x1",
      ordem: "5as651651",
      data: "2018-01-23"
    };
    console.log('res', string, obj)

I’m trying to do it this way

for(item in obj){
  console.log(item, obj[item]);
  console.log(string.replace(new RegExp('${'+item+'}', 'g'), obj[item]));
}

I go through all keys of the object and for each key I do the replace, but test way is not working, too :(

Answer 1

You can use a function as the second parameter of String.replace().

She will receive as arguments:

• match: the married string in Regexp
• g1, g2, g3, ...: the cadate groups in Regexp, may be 0 to N, depends only on your Regexp.
• offset: the position in the string where the substring that matches Regexp was found
• string: the full string

Then a solution could be, create a Regexp that marries with ${...}, group what is inside the keys, test if it exists in the object and replace the contents.

Ex.:

string.replace(/\${(.*?)}/g, (match, group, offset, string) => {
    return group in obj ? obj[group] : match
})

The regex will marry ${...} always grouping what is in ... and inside the function testo if there is the key in the object. If there is replaced, it keeps the same string.

---

Example running with your code:

let string = 'PP24,260:AN7'+
    'BARSET "QRCODE",1,1,11,2,1'+
    'PB "${qrcode}"'+
    'PP 270,265'+
    'PT "${cliente}"'+
    'PP 270,225'+
    'PT "${comprimento}"'+
    'PP 270,185'+
    'PT "${diametro}"'+
    'PP 270,145'+
    'PT "${espessura}"'+
    'PP 270,105'+
    'PT "${aco}"'+
    'PP 270,65'+
    'PT "${peso}"'+
    'PP 550,145'+
    'PT "${lote}"'+
    'PP 550,105'+
    'PT "${ordem}"'+
    'PP 550,65'+
    'FT "Swiss 721 BT",11'+
    'PT "${data}"'+
    'LAYOUT RUN ""'+
    'PF'+
    'PRINT KEY OFF';
    
let obj = {
    qrcode: "asd1231",
    cliente: "1321384a684a654a564z6",
    comprimento: "1256.2",
    diametro: "13.5",
    espessura: "26.5",
    aco: "3695z",
    peso: "165.00",
    lote: "65zxc651z3x1",
    ordem: "5as651651",
    data: "2018-01-23"
};

let x = string.replace(/\${([^}]*?)}/g, (match, group, offset, string) => {
  console.log(`
    match: ${match}
    group: ${group}
    return: ${group in obj ? obj[group] : match}
  `);
  return group in obj ? obj[group] : match
})

console.log(x)

Answer 2

You can do this natively using strings template Javascript. For this, you will change the ' of the string by ` and will directly access the properties of your object within the string template:

let obj = {
      qrcode: "asd1231",
      cliente: "1321384a684a654a564z6",
      comprimento: "1256.2",
      diametro: "13.5",
      espessura: "26.5",
      aco: "3695z",
      peso: "165.00",
      lote: "65zxc651z3x1",
      ordem: "5as651651",
      data: "2018-01-23"
    };

let string = `PP24,260:AN7
    BARSET "QRCODE",1,1,11,2,1
    PB ${obj.qrcode}
    PP 270,265
    PT ${obj.cliente}
    PP 270,225
    PT ${obj.comprimento}
    PP 270,185
    PT ${obj.diametro}
    PP 270,145
    PT ${obj.espessura}
    PP 270,105
    PT ${obj.aco}
    PP 270,65'+
    PT ${obj.peso}
    PP 550,145
    PT ${obj.lote}
    PP 550,105
    PT ${obj.ordem}
    PP 550,65
    FT "Swiss 721 BT",11
    PT ${obj.data}
    LAYOUT RUN ""
    PF
    PRINT KEY OFF`;

console.log('res', string, obj);

Note that it is very elegant to create the string, as it is no longer necessary to worry about concatenating it and replacing variable value markers.