A Graph representation with JavaScript ES6

graph.js

class Graph {
  
  constructor(){
  	this.nodes = [];
  	this.edges = [];
  }
  
  addNode( node ){
     if( !this.hasNode(node) )
       this.nodes.push(node);
  }

  randomSeed( number ){
    let i,j;
  	for(i = 1; i <= number; i++)
      this.addNode(i);
    
    for(i = 1; i <= number; i++)
      for(j = 1; j <= number; j++)
        if( i != j )
          this.addEdge(i,j, Math.floor( Math.random() * 100 ));
  }
  
  hasNode( node ){
    for(var i in this.nodes )
      if( this.nodes[i] == node )
        return true;
      
     return false;
  }

  hasEdge( n1, n2 ){
    const edges = this.edges;
    for(var i in edges){
      if( 
        ( edges[i][0] == n1 && edges[i][1] == n2 ) ||
        ( edges[i][1] == n1 && edges[i][0] == n2 )
      )
        return true;
    }
      
    return false;
  }

  addEdge( n1, n2, size){
    if(
       this.hasNode(n1) &&
       this.hasNode(n2) &&
      !this.hasEdge(n1, n2) ){
      this.edges.push([n1,n2, size || 0]);
    }
  }
}

var test = new Graph();
test.randomSeed(15);
console.log(test.edges.length);