vue中forEach循环的使用讲解

//data为集合 
data.forEach(function(item, index) {
            //item 就是当日按循环到的对象
            //index是循环的索引，从0开始
})

getCrumbs(){
    let crumbs = JSON.parse(localStorage.getItem( "crumbs" )); 
    //[Vue warn]: Error in created hook: "TypeError: Cannot set property 'manageClass' of undefined" 报错
    crumbs.forEach(function(item){           
        console.log(item);                    
        if (item.name === "staffInfo") {
            this.manageClass = item.manageClass
            this.infoClass = item.infoClass; 
        }
    })
    
},    

crumbs.forEach(item => {
    console.log(item);                    
    if (item.name === "staffInfo") {
        this.manageClass = item.manageClass
        this.infoClass = item.infoClass; 
    }
})

 getCrumbs(){
    let crumbs = JSON.parse(localStorage.getItem( "crumbs" )); 
    //[Vue warn]: Error in created hook: "TypeError: Cannot set property 'manageClass' of undefined" 报错
    // crumbs.forEach(function(item){
    crumbs.forEach(item => {
        console.log(item);                    
        if (item.name === "staffInfo") {
            this.manageClass = item.manageClass
            this.infoClass = item.infoClass; 
        }
    })
    //  或者使用for循环
    for (let i = 0; i < crumbs.length; i++) {
        if (crumbs[i].name === "staffInfo") {
            this.manageClass = crumbs[i].manageClass
            this.infoClass = crumbs[i].infoClass; 
        }                  
    }
},