update
标准形式materials.map(function material){ return material.length;}
=============================================================================
Arrow function restorevar materials = [ 'Hydrogen', 'Helium', 'Lithium','Beryllium'];
console.log(materials.map(material => material.length));写出这个的标准函数形式，就像下面这个形式一样(var selected = allJobs.filter(function job) { return job.isSelected();});
var selected = allJobs.filter(job => job.isSelected());
先画饼。
转载于:https://www.cnblogs.com/kazama/p/9940870.html
