Concatenate a string to each object of an array

Question

I have an array looking like this:

myArray = [[EnterNode {name: "name1", _value_: 12.32 }],
           [EnterNode {name: "name2", _value_: 42.39 }],
           [EnterNode {name: "name3", _value_: 77.32 }],
           [EnterNode {name: "name4", _value_: 52.31 }],
           ...
]

I don't know what EnterNode means but this is how it looks like when I print it in the console.

I want to each _value_ to concatenate a string, for example " kg" so after this procedure the array to look like this:

myArray = [[EnterNode {name: "name1", _value_: "12.32 kg" }],
           [EnterNode {name: "name2", _value_: "42.39 kg" }],
           [EnterNode {name: "name3", _value_: "77.32 kg" }],
           [EnterNode {name: "name4", _value_: "52.31 kg" }],
           ...
]

I tries to do it like this:

myArray.forEach(_value_ => _value_ + " kg") but I get undefined as result.

Any suggestions?

Use `.map` instead of `.forEach`. Foreach doesn't return anything, whereas map returns a copy of the modified array — user184994, Dec 27 '17 at 12:46
did it like that and my array contains now these: `"[object Object] kg"` — Leo Messi, Dec 27 '17 at 12:49
Not exact duplicate but should help you: https://stackoverflow.com/questions/16691833/modify-object-property-in-an-array-of-objects — Rajesh, Dec 27 '17 at 12:53

score 1 · Accepted Answer · answered Dec 27 '17 at 12:48

myArray.forEach(value => value + " kg") but I get undefined as result.

Because you are not saving the value back to _value_ property of each item of the array

Make it

myArray.forEach( obj => ( obj._value_ += " kg" ) );

observe that iteration happens on the item of the array rather than _value_

Demo

var myArray = [
   {name: "name1", _value_: 12.32 },
   {name: "name2", _value_: 42.39 },
   {name: "name3", _value_: 77.32 },
   {name: "name4", _value_: 52.31 }
];

myArray.forEach( obj => ( obj._value_ += " kg" ) ); 
 
console.log( myArray );

Concatenate a string to each object of an array

1 Answers1