JSFiddle - React, Tailwind, and code Playground

JavaScript

var materialStd={flow:123, name:'Raoul'};
  var obj={
    id:0,
    line:[
      {id:1, material:materialStd},
      {id:2, material:materialStd},
      {id:3, material:materialStd}]
      }

	testerror();

  function testerror(){
    console.info(obj);
    //On appel une fct test

    console.log(''+obj.line[0].material.flow);
    console.log(''+obj.line[1].material.flow);
    console.log(''+obj.line[2].material.flow);

    test(obj);

    console.log(''+obj.line[0].material.flow);
    console.log(''+obj.line[1].material.flow);
    console.log(''+obj.line[2].material.flow);

  }

function test(objetTraiter){
//  objetTraiter.line[0].material.flow=1;
// objetTraiter.line[1].material.flow=2;
  objetTraiter.line[2].material.flow=3;
console.log(''+objetTraiter.line[0].material.flow);
console.log(''+objetTraiter.line[1].material.flow);
console.log(''+objetTraiter.line[2].material.flow);

}